The problem with men only groups was that they were the centre of power, especially the mens clubs in London whose members were MPs, industrialists etc. Like men's locker talk and so on.
I can see why one way women could make progress to euality was by not allowing to have those retreats where business could be discussed but women could be exclude.
I think the difference is really a uestion of function. A men's choir, a women's choir. Even the Rugby club dinner! - but then rugby clubs now have women's teams - of which I am deeply envious. I would have loved to haveplayed rugby, when I was a child. Football held no appeal, but rugby, but then it was a men ony game.
I think there is something deep in most people's psyche that means that at times they wish to meet in single sex groups. It is how this can be done without it also being exclusionary from a wider group. For example in the past, rugby was a male only game, women were not allowed to play the game and because all rugby pitches were in male hands, it was impossible for women to play the game because they had no access to a rugby pitch.
Legal ban on smartphones, schools in England
A famous matador gored by bull!


) women routinely defer to men, and are reluctant to talk about some topics in front of them. Men can shift the dynamic, and not all groups would benefit from that. That is why the reading group I'm in decided not to allow men to join. We felt that there would be more risk of being shouted down, or having the ideas we'd expressed being rehashed and presented as coming from a man. Our group can get heated, but it is generally supportive.