I’ve watched some here and there, but having to try to catch them when they stream has put me too much in the mind of old tv and catching shows when they air. Watching the recording afterward is maybe good for some white noise, but it’s clearly not the intended experience I think.
I don’t personally care to catch live streams and participate, but I do sometimes prefer a streamer’s commentary on a game compared to pure gameplay.
There was a streamer’s series I used to watch (Attacking Tucans playing Zelda OOT randomizer). Their personality and reactions to the game were fun to watch and added to the experience.