Is it news when something doesn't happen? You need to establish the foundation that it was supposed to happen and something prevented it. Maybe most news organizations decided that to say these rallies didn't happen is to say that there are very few people dedicated to this cause, and that's not something they want us to believe.
The way NBC News dealt with that is to say that the failure to show up in person should be interpreted to mean that the movements have gone "underground." So a big rally would be bad, but a non-rally would be bad too:
The poor showing underscores how the country’s unpopular and disorganized extremist movements have been driven underground by increased scrutiny from the media, law enforcement agencies and far-left activists who infiltrate their private online spaces and disrupt their attempts to communicate and organize.
How do you know that what looked like rally planning wasn't just the media, law enforcement agencies, and far-left activists talking amongst themselves?