Who could have predicted that constantly saying all men are trash could have negative impacts???
And to be clear in no way am excusing the behavior of people who respond in this fashion, but I can also understand how they ended up where they did.
I completely understand hating some people from any category of anything, but when you broadly blame ALL of a group you are absolutely going to alienate people who were either on your side or neutral. I think this is exactly what happened to a lot of guys. They were just sitting there minding. Their business and suddenly they are being told that they are inherently evil and shitty just because they are men. They hear it on the news and on social media. Pop culture takes a shit on them too once in awhile.
It doesn't exactly take a rocket scientist to see how this could end up twisting around in the minds of some of them.
I don't have the specific answers for how to combat this sort of stuff completely, but I think a good starting point would be to have more targeted criticisms as opposed to just going after an entire gender broadly. I think that has clearly done more damage for gender relations than it has helped anything so far.
Just my 2 cents as a guy who has seen some old friends who were once self proclaimed feminists now go full on into hating women. It's sad to see.