Some of them did, they were forced by their respective courts to be inclusive to all.

and should have just moved to form their own men-only spaces

In CA? Those are illegal except in very narrow exceptions. In most other places they’d be subject to anger, protests, and might be illegal there too (state laws are all over the place on anything that’s up to the states).

Like Title IX, everyone loves the idea of a law mandating that you can’t discriminate right up until someone who’s an “acceptable” target for discrimination makes use of it. See basically any time a boy has invoked Title IX.

My personal favorite example of that being feminist philosopher and icon Mary Daly, who’s teaching career ended due to Title IX because she refused to teach male students.

MRAs are idiots

Ironically, MRAs would love to see the Equal Rights Amendment (so long as it doesn’t include the Hayden Rider or similar) or a federal version of Unruh passed more than anything else. But then it would immediately be used to attack things with explicit sex discrimination like differences in pricing based on sex, differences in facilities offered based on sex, Selective Service, VAWA (actually not sure if the last re-authorization cleaned up the relevant language or not) and the ACA (the contraceptive mandate explicitly only applies to contraceptives for women, including barrier and surgical methods - this means that for example there’s no requirement to cover vasectomy and if vasalgel or the like ever hits market there would be no requirement to cover that either). Likewise, if women are ever required to sign up for Selective Service it will launch dozens of lawsuits across a bunch of states because a bunch of states require men to provide their selective service number to qualify for various things.