That's a far narrower view on hobbies than most people would define it as. "Mental" stimulation typically counts as leisure activity. To the extent that no one sniffs at the idea of saying "watching movies" is a hobby of theirs.

Appreciating/critiquing art at an art show--or attending a certain style of social event on a monthly basis--certainly requires more active participation than spending time in a theater.

And if you doubt what sort of time investment an anime fan would require in keeping up with their hobby, take a look at much material someone would have to keep up with in just a three-month period alone: https://myanimelist.net/anime/season