But for your example it isn't needed whatsoever. They do what they want without it. Denigrating a good initiative by association with a small number of suspect participants is not convincing.

"Or maybe even Google and Facebook making anti-tech protests less visible because black bloc may show up."

Google and Facebook can do anything and everything they want right now. And we know that they, among others, bring forward the most contentious and the most divisive because it draws engagement. We know that they immerse people in their own filter bubble where suddenly they live in a world where seemingly everyone is a flat Earther, or believes in Pizzagate, or whatever.

"so the problem isn't technology, it's humans"

This is specious. In a period of ignorance, ignorance reigned supreme (not to mention a theocracy, which is dangerously close to re-emerging in the US). We now, at least in some realms, have an ability to reason and to cite and use fact.