if you don't think predominant femaleness is something to value, then that line is of course going to annoy or even offend you.

It's not just that, but also, when I read that someone values fandom being female as the #1 thing, it feels to me like they are only tolerating people who don't identify as female, and furthermore that they are invested in actively keeping it that way (such as by the rhetoric of "for women, by women").

(This is not necessarily about OTW, but this slice of fandom in general.)