If all you're doing is googling for mature, well-curated answers, then you're not seeing this. Go post a "dumb question" and see how you're treated.
And the contention isn't that people are being deliberately mocked, it's that they don't feel welcome, which is a different thing.
So... how might a woman (or whoever) not feel welcome? Maybe because the forum she's on sees people regularly doing stuff like saying discrimination is "not even possible", or mocking those talking about it for "pointless virtue signaling"? I mean, seriously: go back and read the very post you just typed: does that seem "welcoming" to you?
It's not.