You'll note that most people saying this stuff are being extremely non-specific about what it means. My impression is that a lot of what they want to do would be offensive to lots of guys as well. Essentially they want a space to act in a way that women would feel quite threatened by. Not that mixed groups don't already have that as an issue.
You couldnt be more wrong in your guessing. The answer lies in games all women play with both men and women constantly, never being truly honest with words, expecting men to pick up meaning between lines, predict their emotions and so on and on. We have enough shit in our lives already, no need to add more.
Its frustrating and tiring experience for all men, thus the need to vent out somewhere else where these dynamics dont play out semi constantly.
I am pretty sure women see it similarly in reverse although details in dynamics are very different.
As a man I don't recognize that game playing as something all women do. It's just not something I've experienced in my relationships platonic or otherwise with women. Maybe it's a Europe vs. America thing (edit: from your other comments, you seem to be in Europe so not that) or something personal to you and your experience but it sounds very 'incel-adjacent'.
Yep, there's always a strong element of "what opinions, motherfucker" goose comic in these discussions. And we always end up at "tell me you're an incel without telling me you're an incel"