"... and you’ll discover how language, like a virus, can mutate overnight. All of a sudden, yesterday’s quotes suffer the insertion of some foreign DNA that makes them easy to weaponize. In this case, that foreign intrusion is a word: 'all.' 'All' insertion was all the rage during the Kavanaugh hearings. When senators from Kamala Harris to Mazie Hirono had their regard for Dr. Blasey’s credibility elevated by Fox News pundits to universal gender credulity, their actual words, 'I believe her,' became believe all women. 'That’s literally the hashtag,' former Fox News contributor Morgan Ortagus said in February 2019.... Is there 'literally' a hashtag? Well, kind of.... Type in #BelieveAllWomen for 2017, when the #MeToo movement took off in October, and you get several dozen references, followed in 2018 (the year of the Kavanaugh hearings) by many more. But here’s the thing: I found that the hashtag is, by a wide margin, used mostly by its detractors. It seems that #BelieveAllWomen first appeared on Twitter in late 2014, in three tweets — by an Ontario midwife.... Then, in the fall of 2015, Hillary Clinton posted a tweet: 'To every survivor of sexual assault … you have the right to be heard. You have the right to be believed.' To which Juanita Broaddrick, who alleges that Bill Clinton raped her in 1978, responded on Twitter on Jan. 6, 2016, 'Hillary tried to silence me.' Conservative editor David French, who has a large Twitter following... retweeted Ms. Broaddrick at once — attaching the hashtag #BelieveAllWomen, followed by four question marks.... As happens, the canard, blown into a bonfire by the right, became accepted truth in mainstream media...."
From
"'Believe All Women' Is a Right-Wing Trap/How feminists got stuck answering for a canard," by Susan Faludi (NYT).
I appreciate that tracking down the origin of a saying that can't possibly be right. It is a good taunt coming from the right, and it's important to know how to keep from getting tangled up in it.
But I can't resist taking a shot at that "canard, blown into a bonfire." A "canard" — as all of us who took French class should remember — is a duck. The French word has been used in English since the 1840s to mean "A false or unfounded story, rumour, or claim, esp. one that is deliberately misleading; (originally) spec. an extravagant or absurd story circulated to deceive the credulous; a hoax" (OED). It's a dying metaphor, so you have to watch out for putting it with other metaphors, like a bonfire. I can't read "canard, blown into a bonfire" without picturing a poor waterfowl bursting into flames...