What is the real "free speech problem" on the left from the point of view of a real leftist?

I'm reading "Do Progressives Have a Free Speech Problem?/The illiberal left is a lot less threatening than the right. That doesn’t mean it doesn’t exist" by Michelle Goldberg (NYT). Goldberg signed the "Letter on Justice and Open Debate" that was published in Harper's, and she's using this column to expand on the topic.

She says she initially declined to sign the letter, "in part because it denounced 'cancel culture'" — a term she associates with "right-wing whiners like Ivanka Trump who think protests against them violate their free speech." I'd like to see the first draft! I want to know what had to be taken out to get so many signatures. At least we know what one person says she objected to and that it was, she says, edited out. Goldberg notes that discussions of the letter have talked about "cancel culture," even though the words aren't in the draft.

After avoiding writing about the subject — telling herself other things are more important — she got triggered by the "scathing rejoinder" written by Hannah Giorgis (in The Atlantic):

“Facing widespread criticism on Twitter, undergoing an internal workplace review, or having one’s book panned does not, in fact, erode one’s constitutional rights or endanger a liberal society.”

This sentence brought me up short; one of these things is not like the others. Anyone venturing ideas in public should be prepared to endure negative reviews and pushback on social media. Internal workplace reviews are something else. If people fear for their livelihoods for relatively minor ideological transgressions, it may not violate the Constitution — the workplace is not the state — but it does create a climate of self-censorship and grudging conformity....

John McWhorter, an associate professor of English and comparative literature at Columbia who signed the Harper’s Letter, told me that in recent days he’s heard from over 100 graduate students and professors, most of them left of center, who fear for their professional prospects if they get on the wrong side of left-wing opinion.

Some on the left have argued, fairly, that those worried about people losing their jobs for running afoul of progressive orthodoxies should do more to strengthen labor protections, since all sorts of employees are vulnerable to capricious termination.... But it seems strange to me to argue that in the absence of better labor law, the left is justified in taking advantage of precarity to punish people for political disagreements.

There, she's rejecting the idea of putting left-wing political goals (better labor law) ahead of free speech. But she does flag a real argument that she says exists on the left: Let the opponents of strict labor laws experience the pain of firing just for saying the wrong thing so they'll come around and support our legislation. "Some" are saying that, but Goldberg declares it "strange." Is it "strange" that the left would sacrifice free speech as a means to an end it thinks is more important? Or is it just too openly offensive to work and "strange" to think that it could?

None of this is an argument for a totally laissez-faire approach to speech; some ideas should be stigmatized.... But it’s a problem when the range of proscribed speech is so wide that the rules are hard to even explain to those not steeped in left-wing mores.

Now, I'm starting to get the feeling that the "problem" for the left is that its position on free speech is hurting its overall agenda. It's good to stigmatize ideas, but so many ideas are stigmatized that ordinary people — people not "steeped in left-wing mores" — can't even understand what they're not supposed to say. If you put their jobs at risk and you can't "even explain" what the firing offense is, then "it's a problem." It's a problem because it's outrageously unfair and repressive? Or is it a problem because the left-wing will trigger opposition if it scares the hell out of people?

Writing in the 1990s, at a time when feminists like Catharine MacKinnon sought to curtail free speech in the name of equality, the great left-libertarian Ellen Willis described how progressive movements sow the seeds of their own destruction when they become censorious. It’s impossible, Willis wrote, “to censor the speech of the dominant without stifling debate among all social groups and reinforcing orthodoxy within left movements. Under such conditions a movement can neither integrate new ideas nor build support based on genuine transformations of consciousness rather than guilt or fear of ostracism.”...

Aha! The quote from "the great" Ellen Willis comes right out and admits that freedom is not an end in itself and what matters is the political agenda of the "left movement." You want to encourage people to join by inspiring real belief. Scaring them and guilt-tripping them into orthodoxy — Willis claimed — won't build the foundation you need for the movement. In Goldberg's words, the left will "sow the seeds of their own destruction" if it chooses censorship as its means to its end.

Of the conservative campaign against political correctness in the 1990s, [Willis] wrote, “Predictably, their valid critique of left authoritarianism has segued all too smoothly into a campaign of moral intimidation,” one “aimed at demonizing egalitarian ideas, per se, as repressive.”

The same is happening today; the president throws tantrums about “cancel culture” while regularly trying to use the power of the state to quash speech he dislikes.

What does that refer to? I don't know.

Because Trump poisons everything he touches, his movement’s hypocritical embrace of the mantle of free speech threatens to devalue it, turning it into the rhetorical equivalent of “All Lives Matter.”

That is: It hurts the left to allow the right to have possession of the free speech banner, the left-wing agenda is the end, and the position on free speech should be crafted to serve that end.

But to let this occur is to surrender what has historically been a sacred left-wing value.

I think, to be honest, Goldberg ought to replace "what has historically been a sacred left-wing value" with what the left has from time to time presented as a sacred value. I no longer believe the left ever had this value, only that it used the idea in its rhetoric when it wanted more free speech for itself or when seeming to have this value worked as a means to an end.

And Goldberg isn't embracing free speech as a sacred value! She's saying that the theater of holding free speech sacred is too effective to cede to the right.

One reason many on the right want to be seen as free speech defenders is that they understand that the power to break taboos can be even more potent than the power to create them.

That's one of those sentences you have to rewrite to understand. Let me try: By making speech taboo, the left empowers the right to seem heroic for championing freedom. Again, that's about means and ends. Punishing people for saying the wrong thing is a bad choice of means, because instead of concentrating on why one ought to believe the right thing, you let your antagonists avoid the substantive debate and attack you for opposing freedom of speech.

Even sympathetic people will come to resent a left that refuses to make distinctions between deliberate slurs, awkward mistakes and legitimate disagreements.

So... maybe some punishment of speech would work well as a means to the accomplishment of a left-wing agenda, but because the left has reached so far in defining what speech is punishable, people — even people who would be inclined to support the left — are roused from their complacency. It doesn't work, so it's not a good idea.

Cowing people is not the same as converting them.

Again, we see the goal: winning converts for the left-wing agenda.

Now, I say freedom is an end in itself, but that's not the only basis for supporting freedom of speech, and Golberg's last sentence — "Cowing people is not the same as converting them" — does point at another reason — a strong reason — for supporting free speech that I think is worthy and important. This is the idea that people have minds and they should hear a free and open debate so they can choose for themselves what to believe. You can compel people to outwardly manifest a belief, but then — if they have some depth and consciousness — they don't really believe. You just get shallow acquiescence.

If you're really dedicated to your political agenda, however, you might think: I don't care how deep or shallow the populace is. I just want my group in power.

And isn't that what lefties think is always going on anyway — groups acquiring and consolidating power?