I think some of them definitely post in some attempt to sway public opinion towards their way of thinking, which obviously benefits men. i.e. they don't like the idea of women being too "militant", thinking for themselves or discussing things with other women, so some of them pop on here and try to use their imaginary Great Influence on the way women think, believing that it will work.
I've not been here all that long, but I've experienced two try that in the last week. One got very irate on a thread where I pointed out that a lot of young women now were considering that being single was a perfectly good option if a man couldn't add something to their lives. Apparently, according to that male poster, this meant that I was going to struggle to attract men on internet dating and he did make some vile abusive comments about me which I must admit I didn't bother to fully read and reported to mumsnet. The comments might have been deleted as a result - I didn't check.
Then there is current thread where there is a man posting quite persistently. I thought his views sounded as though it was a poster who had never actually dated a man, and when I said this he stated that he was indeed a man (therefore assuming he is heterosexual, I was correct). But he kept repeating his odd views, over and over again, of how women should be happy to host men for sex once a week or fortnight and go on free dates. Apparently, according to him, dates were not measured on their cost. Clearly they were measured on their lack of cost, but anyway I did point out to him that he was utterly delusional and advocating casual sexual relationships that would appeal to very few actual, real women unless they were specifically looking for FWB.
tbh I find these sort of posters very entertaining, and they are nearly always very predictable and can always be relied upon to in a certain way if you make a certain type of response to their posts! Most of this type tend not to be that bright, assume everyone is easily taken in, and obviously they struggle to attract women or women of the type or in the numbers they would ideally like. In real life, obviously most of us wouldn't give these types the time of day but it is an interesting insight sometimes into how much some men struggle to attract women and how few options they would ideally like women to have in order to attract them.