Cali is "the" place to be for this kind of work because there is the most opportunity there. It was easy, for example, for Projared to collaborate with Game Grumps (and fuck Ross' wife) because they were in the same area. Same with virtually any collaboration GG has done for the most part.
It's also a big hub of Video Game Journalism because a lot of Video Game studios are centered there. Correspondingly, there are also a lot of Voice Acting/Anime Studios there as well on top of a lot of other tech/corporate headquarters. It's a very good hub to be in, if that's what you want your world to be. It's way easier to collab with other artists, it's way easier to attract sponsors when you can meet in person, it was easier to branch out into other "video game" areas/jobs.
(See also but to a lesser extent - Montreal, Seattle, Austin/Dallas, Boston)