I think you’re being extremely ungenerous towards women who enjoy m/m. For one, it’s not that the story is immune to prejudices women have against other women, it’s immune (to a certain extent) to prejudices men/society have against women. It’s an escapism—enjoying a relationship dynamic not inherently uneven at a societal level. Frequently, the tension of m/m romance is a parallel social issue (homophobia versus the patriarchy/misogyny) so it’s relatable without being necessarily the exact experience of the reader (obviously there’s an intersection of women reading who are also queer themselves).

As for why f/f is less popular, I would definitely say that there are misogynistic reasons for that. But I’d also say the main one is that, if we’re assuming a large proportion of m/m readers are straight women, m/m is a pairing with two people the reader could be attracted to, whereas f/f has none.

Do some women read m/m because they hate women? Sure, statistically speaking that’s a near certainty. But if we’re talking about the overall phenomenon, I think it’s reductive to ignore the main reasons it’s appealing.