I wish I could upvote this more than once; it aligns neatly with several things I've been wanting to say for months but haven't found a chance to. There's just a couple things I'd like to add.

First, I suspect the relatively small size of the MRA sphere distorts outsiders' perception of it in ways other than making hateful personalities proportionally more common. Specifically, it's too small and too new for well-developed sub-movements to be self-sustaining: there are identifiable tendencies (compare the average comment on Spearhead to the average on Owning Your Shit [ETA: or not; see below]), but there's far more cross-posting between them than on comparable feminist sites, and I'd attribute this directly to feminism's far greater age, size, and level of development as an ideology. Since not a few prolific cross-posters fall into the "hater" category, and since offensive comments are always going to be disproportionately salient to readers, this ends up tarring the whole community.

But that's just a perception thing, more or less. Even if a viable egalitarian-looking men's advocacy programme manages to magic itself into existence, I think problems might be still caused by the likelihood that both these movements conceptualize themselves as the true standard-bearers of equality, and blame any remaining inequalities the other side's concerned about on failures to incorporate their own theoretical frameworks. Probably the most common feminist objection I've seen to more moderate (i.e. non-traditionalist, positive-sum) MRA ideas is precisely this: feminism objects to the same problems (discrimination against men as caregivers, narrower culturally acceptable affect and presentation, etc.) and they'd allegedly vanish in a fully feminist society, so why not just call yourself feminist and work with established approaches to privilege, misogyny, etc.? And this isn't one-sided, either; I've seen almost identical sentiments from moderate MRA sources, with appropriate nouns and theory swapped.

The answer, as best I can figure, is that each theoretical framework is built up to explain a particular set of salient experiences, and since few data points outside those experiences make it into the working set we end up with a tendency to overfit. This is of course exactly the problem that third-wave feminism already confronted regarding intersections with queer theory, race, etc., but intersectional integration seems harder in this case -- perhaps because MRA, even the moderate kind, doesn't draw upon the same intellectual traditions.