I'm not big on streams either, but the main reason I watch the occasional clip or archived stream (and Lets Plays when those were a thing) is to see people react to games I've played in the past- it scratches that same itch you got when you had a friend over to have them play or watch something

I also study Japanese for fun and have always liked Japanese gameplay videos from that angle, so Vtuber content being so prevalent is a boon in that regard even if I find the broader fan culture kind of grating