Parmandur
Book-Friend, he/him
Well, the folded ia the incorrect premise: streaming RPGs are not mostly CR, not by a long shot. They are a major stream, but they are not even the largest audience among TTRPGs.Stranger Things and the rise of streaming games (which is mostly CR).
And when CR has done non-D&D games, they have a smaller audience. A fairly large chunk of CR viewers are there to watch them play D&D specifically more than to watch them play anything.