I think you're mistaking your experienced distribution for the true distribution. Like, I'm very willing to believe that of the MRAs you're aware of, they are all hardcore -- it's a demonized subculture, you'd have to be a zealot or have fuck-you money to come out supporting it.
If instead of defining MRAs as "people posting crazy things to (insert website here)" you simply call an MRA someone who's primary political activity is toward fixing issues MRAs discuss, you'll be able to find a large number non-hardcore MRAs with a couple of google searches. Heck, I think most people working professionally with prostate cancer would qualify. The guy in this thread who mentioned lurking on MRA forums for interesting ideas absolutely qualifies (or rather, he didn't sound hardcore to me on first read).
Similarly if you go looking for the equivalent of (insert MRA website here) for feminists, you will also succeed in that endeavor. Your comment re: hardcore Roman Catholics & Branch Davidians makes me think perhaps you haven't gone looking for these sorts of sites.
Which is to say, yet again, that I do not believe the equivalence is false. I'd even go so far as to say that I expect the rates of hardcore ideologues in each group to roughly correlate with the rates of paranoid delusion in men and women respectively.