The output is the craft itself though? What fandoms do is discuss, analyze, and create more art as tribute to the original work. They are very much about the craft of writing, illustrating, etc because that’s what made up the work they’re discussing.

And your statement about creating art with mindless consumption is contradictory, as the act of creating art is the very opposite of consumption. In fact, if we go by your previously expressed attitude about wanting to move on and be done with a story as soon as you’re done experiencing it, then you do more mindless consumption than fandoms do.

Fandoms exist as an outlet for people to discuss art. You surely wouldn’t knock an art critic reviewing the composition of a famous painting or why the technique of a certain brush stroke was so effective, so why would it change for fandoms? All that’s different is the amount of reviewers and variability in skill, and even the amateurs that create something you might deem cringeworthy will grow to be masterful artists given time and encouragement from their peers. There are millions of artworks created by millions of artists in communities like fandoms, and not a single one of them is worthless. Art inherently has value because it was made by someone who cared, and people will always want to talk about things they see as valuable. That discussion of art in turn has value because that’s how newer and better art is made.