Twitter isn't healthy for _anyone_. Neither is the vast majority of social media. The way in which most sites currently structure interactions lends itself quite naturally to misinformation, extreme polarization, and resulting anxiety.
I've personally witnessed the effect on reasonably well educated adults in my life; I can only imagine how much worse it must be for those with less general experience and knowledge.
It's when the person in question is mentally ill or socially isolated (i.e a NEET living in their mother's basement) that radicalization becomes harmful, because there's nothing to bring them back to the baseline. Marginal identities attract marginal people.
(I have a theory that online transgender-ism is spreading in exactly the same way - note the massive amount of trans people online who are also NEETs, weebs, and/or communists. But that's a story for another day.)
Beyond that, I think you are quite off base in comparing trans people to online Communist and neo-Nazi radicals. You are probably looking at a much narrower slice of the trans population than you think you are. Assuming that you don't actually have some kind of anti-trans agenda, I'd rethink how you're expressing whatever point you're trying to make here.
As someone without a Twitter account, I miss out on a huge amount of conversation that IMHO can add productive and interesting insights to, even though I’m not well-known like the participants might be. With time, they might come to know me as well, something which is basically impossible outside of the platform. I have heard that it is also a great place to find jobs or the right people through “the Twitter network” where people are known for what they tend to be good at and people can point you around to where you need to be.
On the other hand, having the ability to get random people to interact with you is basically inviting harassment and polarization. The very benefit I just mentioned of having a “personality” in Twitter which people see you as means that you’ll always be dragged into any conflict along those lines, and anything you say has the potential to blow up in a bad way.
I, from outside the platform, have a much harder time getting any of those benefits I mentioned: fewer people read or look at my stuff, I think, since I publish it elsewhere; I have hundreds of things I leave unsaid because I can’t interact with the platform besides observe it; getting in contact with people who share my interests is much more difficult because I’m often cold emailing them or collaborating with them on something before they know me. I don’t get to know about interesting work opportunities very often. But on the flip side, I don’t get dragged into pointless arguments, at least on that platform, so I guess I’ve just been making that tradeoff ¯\_(ツ)_/¯
