People have been following this strategy of creating their own mini-brands for years and have their own following. YT doesn't even have all of the their content, and YT is just one lead gen channel. Frankly, Ad Revenue from YT is pitiful, and it's an open secret the real money is made as I've described (although it is a long term play).
I don't disagree with you about PeerTube and the like, but it is a two-sided marketplace and you need to prime both sides of that pump (content creators and viewers).