There are some benefits to using "male supremacists" instead of "the patriarchy".

The latter word has much in common with the not-great parts of wokeness including it's tendency to blame vague nebulous faceless systems.

"Male supremacist" isn't a term that belongs to any specific ideology so it's more up for grabs and less likely to be used as a punchline than the patriarchy (the right wingers are already mocking it like they do woke culture terms).

It also meshes nicely with the frequently used "white supremacist". It benefits feminism as it is a reminder to take misogyny seriously. Example: comparing the insulting vibe many get to transracially-identified Rachel Dolezal's opting in to an oppressed category to transwomen taking over womanness.