>>13883121A lot of the big names on Twitch have edited highlight channels on YT.
Asmongold does, so do some of the others. It allows them to reap the benefits of VOD views while still streaming on Twitch, and also serves as advertisement on a different platform.
Vtubers sorta just roll with it and, thanks to the clip meta being in-tune with how YT's algo works (by sheer brute force funny enough), Hololive has come to absolutely dominate the english-speaking vtuber market.
You choose Twitch if you're willing to put in the huuuugggee hours. For the ones moving over, they're basically being given extremely generous contracts that have far less hours in the "You must stream X hours a month" category, as Timthetatman and Ludvig have both stated. This coincides with Twitch pulling back on how much they're offering on their contract renewals, so...