This may have more to do with comorbidity than autism unto itself, but I'm far from an expert on the subject.

I just find it strange how the 1980s-1990s saw a huge boom of literary publications within the fandom, many with well-developed characters and intricate plots, that now seem completely absent.

Money is one part, yes, but I wonder if interest in books and comics has waned (together with peoples' desire to create them).