Also, literally who cares. This isn't politics. Zoomers and millenials are very left-wing and that hasn't changer significantly in recent years. This isn't happening at scales that are shifting the political landscape. Idk why there is an obsession with this shit.
Men aren't leaving the left over this, but men who are unhappy with their material conditions, who might otherwise get pipelined left, are getting pipelined right by this shit instead. It's not a loss, but a lost opportunity.
And you're right that the left isn't mistreating these guys, we're just giving them nothing. If a guy starts googling around about how to find a girlfriend, he gets either bland platitudes or a fast track to the alt right. There is no purpose-built "how to talk to women" equivalent on the left.