Yep. Yep, yep, yep. And Twitter's response is to ban some, but not all harassers, using the algorithm of "whoever is high profile and we don't like politically." That gives said harassers surprisingly legitimate reasons to claim censorship by Twitter as a company, despite the fact that they were in clear violation of Twitter's ToS and deserved to be banned. I refer of course to the Milo Yiannopoulos situation (edit:…
I have personally lost the belief that you can actually change someone's opinion on almost anything. So an echo chamber doesn't have to be a bad thing. I think people overestimate the value of having your beliefs challenged, does it ever really change someone's mind? If that's the case, you might as well view twitter as entertainment and to clue into the things you care about, in which case it can be pretty useful.
Rational arguments, a bit of rhetorical ability, and persistence are surprisingly effective. The problem is the persistence part requires multiple interactions over months or years, so it's hard to study.