Ducky also did a stream on Twitch mostly about this topic:
In terms of alternative platforms he mostly talks about Rumble and Kick. His main complaint with Rumble was that it has ties to political cast-outs on the right like Trump and that one guy with the lips whose name I can't remember. I haven't really seen a wave of vtubers talking about going to Rumble, so I don't know why he's bringing it up except to virtue signal his politics, but yes, if you kick these people off of the traditional platforms, then they go off to alternatives to keep doing what they do. With Kick, he objected to the founder's connection with a cryptocurrency casino and how the site has become a refuge for gambling streamers kicked off of Twitch. I can understand having an aversion to gambling, since it preys upon addiction-prone people, but so do tobacco companies and drug and alcohol companies and porn mongers and fast food restaurants and social media apps and so on, and at the end of the day if we're not going to ban everything in the world that some people cannot responsibly handle, then we need to allow adults to make their own decisions. And while you're going to find gambling streams on the front page of Kick, it's easy enough to just ignore them and find what you're actually looking for. Maybe if one day they force me to run gambling ads on my streams or something like that, I'll reconsider, but for now, network effect aside, I really think Kick is better than Twitch both for viewers (no obnoxious ads) and streamers (95/5 sub cut).
At one point he says something like "you need to really consider before streaming on these sites because it's going to leave a black mark on your career," and he talks about how he judges people who stream on these sites differently than those on Twitch or YouTube. That really rubbed me the wrong way. I don't think "elitist" is the right word for that attitude but it's something like that.
Edit: On the topic of being unwelcome if you're not cis or whatever, I guess it could happen on Rumble given its political bent, but I don't use it myself so who knows. I don't see it happening on Kick, though. I think he's just projecting in that regard.
I personally like to start up and play new games I want to stream for a few minutes well before stream time so I can confirm they work (and hopefully aren't going to dox me) and swap in another game if not, but I guess the pros just wing it. I still have so much to learn.