I don't want to discount negative experiences due to bigotry, these definitely exist.

But besides that, maybe the perceived male-centeredness is real and has to do with the fact that males are more likely to be comfortable with the bare-bones style of what a new technology usually looks like (no offense to the devs who are doing a stellar job working at lightning speed):

Accordingly, in its early days a platform tends to be a sausage fest, and this sets the tone of the conversation for newcomers by default. As the platform grows, and more women join as well, they would feel more comfortable in something closer to this:

The platform itself moves stepwise into that direction, wanting to grow and be more inclusive, usually in order to attract ad revenue. Friction ensues, hostility increases, people feel either stifled or abused or both.

What's so great about #nostr is that vastly more aesthetics and rules of conduct can coexist on the same protocol, than on a single platform! Anyone can use the client(s) they prefer, and use the relays they wish (or even run their own relay). We will definitely run into many novel problems and challenges along the way, but the sheer size of the space of possibilities makes me very optimistic #grownostr