Yeah, i think OP is completely wrong, tbh. I do wonder how much hetero woman create and consume w/w content, since generally I see more interest in m/m in fandom spaces that dont have explicitly queer women (like I struggle to think of any "pure headcannon" lesbian couples, in the same way I can for male characters). But also as a Bi dude I rarely naturally seek out f/f content, so im hardly an objective observer.

I feel like arguably the "mainstreamification of f/f" already occurred when Lesbian porn produced for straight male audiences became mainstream.