Part of the problem with men being part of feminism is that ‘community’ isn’t like it traditionally was used. In most things called ‘communities’, most people know everyone else or it’s run by people who try to be familiar with everyone. Even these days, in small towns, some people will hear about everyone else in town even if you dont’ meet face to face. But communities and movements like feminism- there are people in them that will never ever meet or hear about each other. A privileged person can’t be accepted into a community and have everyone know why and know that it’s because the person’s given signs that they deserve it and aren’t just abusing their privilege and trying to make yet another space all about them.
And a lot of people do abuse that, you get men who claim to be feminists because they think it’ll get them what they want from women or so they can use feminist key-words to attack women who speak against misogyny, you get various privileged people claim to support people they have privilege over so they can take over and get a power trip while getting back-pats from other privileged people.
Whether or not men ‘can’ be feminists, seeing a man who you don’t know claiming to be a feminist is going to be a red flag for a lot of people because of people who do that.
But, really, any man who’s calling himself a feminist really should be aware of his privilege enough to be aware of that and accept it.