I really can't stand watching people play RPGs online. I've struggled to put why into words. I think you're onto something. RPGs are an interactive experience, and watching someone do it is a passive experience. It's not like pure game, like watching a tournament or sports game. There's more to the RPG than just the G.
Maybe the passive experience watching an interactive game is what's making my brain go ow.
For some RPGs are more about the experience than the actual interaction. This has been known and discussed since nearly the start. Usually the player that sits back and does not input much, maybe talking to NPCs and such, but seems to be really enjoying themselves.
Others just really enjoy watching a game being played. Or at least for them, certain types or styles.
Contrast Critical Role with say Zee Bashew, Puffin Forest, or Dingo Doodles for example. One persons going to gravitate to one of those, but possible not have much interest, or even be turned off by, the rest.
Others are more hands on and watching a game, no matter how entertaining, just wont work for them.