Brownshirt gang tactics historically performed real acts against leftists. But if they can't mobilise in numbers that would be useful for doing that then they are effectively wasting their time by existing at all. If they can't perform real violent actions then they're just an annoyingly loud larp group that will be crushed by leftist organising bringing out numbers in the thousands.

Posting social media content isn't terror. If they can't do the terror they're irrelevant.

The stochastic terror you mention is horrible but what's been the effect? Has it hurt the left meaningfully? I don't think it ever has. It's not like the brownshirts in Ukraine storming political meetings to threaten politicians, assassinating leftists or burning down the union building. Those brownshirts are real while these are basically an annoying larp act.