The way I see it is that the most popular content on Steem seems to be very Steem centric. It is like a library where the most popular books are about the Library and who would want to go there. Last time the Youtubers who were looking for a refuge from the continual adpocalypse came they were mainly ignored and votes seemed to still be going to the Steemians talking about Steem posts. (I don't mean any of this as an insult to those who's content this includes, this is just the way it is). To attract and keep content creators we really need to make them feel welcome and for me these new tribes are a great attempt at creating this environment .