I feel like trying to frame men's mental health issues as a problem caused exclusively by "the patriarchy and capitalism" seems like it's trying to wash the rest of society of their own personal responsibility to contribute to making the world a better place for everyone. Patriarchy and Capitalism are just tools of the greater power structure of society, which we all have a hand in forming and perpetuating.
And let's not pretend that the feminist movement's tendency to pump out and empower misandrists and misandrist thinking isn't going to have a negative impact men's mental health, especially if we continue to hold feminism as a scared cow beyond reproach or criticism. And let's not pretend the fact that we have the explicitly female coded "feminism" that opposes the explicitly coded "patriarchy" isn't going to give people who don't have a lot of time to philosophise an inherently combative view of the feminism.
It's hard to buy into the whole "actually femismim is for anyone who wants equality" shtick when you're working exhaustive jobs most your life and then you get exposed to the kind of feminist who says men might as well go extinct because they have sperm banks now.
I'd argue that Valve does more than just take 30% as a middle man. Between Steam Input, Proton, the beta built in recording system, the Forums for every game, community system and the marketplace, having your game on Steam is a massive value generator for the consumer and by extension developers.
30% might not be what the industry standard should be, but Valve isn't just providing a standard digital distribution service.