Well for guys like him he has to consider the financial pain he would seemingly endure if he does choose to stick to his principles. Twitch's platform from a purely streaming point of view might certainly be on the trajectory to being inferior to competitors services, but they still command a lionshare of the viewers for streamers, which will influence the decisions of anyone in his predicament severely.
The main issue I see with guys like him switching to stick to Twitch for pulling a anti-consumer tactic like they did is that if a competitor did get on the same level as Twitch, they would be pressured to implement the similar policies. Most serious streamers won't switch because of the viewer-base, and once the viewerbase crosses a certain population threshold; the greedy assholes from the music/entertainment industry will use their lawyer to spread their paranoia into the service via content flagging algorithms (which almost are always broken/draconian)
A rock and a hard place. It's frustrating to think about and having to abide by convoluted rules and laws that are so short-sighted. They need to be updated but that's another discussion. I see some people say "it's gotta grow more first", now, I don't blame them in saying this but we definitely need to see more support or they will die out. We really do need the competition to foster good growth and good features that improves everyone's streams and experiences.
In Phill Kollar's Polygon op-ed discusion about Twitch there's an interview with ManvsGame, he said he didn't really know of any other streaming services because they all come and go while Twitch has stayed. I could really only shake my head at that. It's not his fault, what he said is true and that's what is saddening.
Even Cosmo said on his stream that he wants Twitch to have competition and hope they Twitch will start improving and doing good things instead of dumb things.
This does not ever need to be a Youtube scenario even though it still kind of is. Youtube is the go to place for everything and the only way for someone to make it big on the internet, it's a monopoly. No one can grow but Youtube. Contracts rule the user generated content and the lives of many, and current copyright laws are old and decrepit and only serve to bully anyone in the new media of the internet.
TLDR: Everything just suuuuuuuucks.