I agree with you to a large extent, Bertrand. I think mostly that's how it happens: a man calls himself a feminist because he has the image of himself as a good guy, someone who loves and respects women, and why wouldn't he support us all being equal?
Where it usually falls down is where that butts up against something the Would-Be Feminist Man holds dear, or isn't willing to give up, or hasn't done the thinking about (and in defence of the WBFM, a lot of women have this too) and his principles give in the face of a real life situation.
I'm reluctant to give examples, though I started to type them out, because I think the examples I give will be picked apart. But I'm thinking of examples like: not pulling weight domestically, enthusiasm about porn and prostitution, being blind to harassment, not being willing to challenge themselves on unthinking biases etc.
So mostly, yes, I think men who say they're feminists aren't, and I agree with feminists who say that men can't be feminists, because it's broadly true, and I get why they say it.
However, if we take a man like Robert Jensen, who has done the thinking, done the critical self reflection, tried his absolute best to challenge all the ways in which he interacts with women and feminism, then I personally am OK with him calling himself a feminist.
Or a unicorn
, because I think he and men like him are rare.