Reading this back it might seem like I don't think women compete, on the contrary, women's MTB series seem to be just as popular and competitive as the men's series and they seem to get just as much television time. I remember being impressed by the coverage the first time I watched the Enduro World Series coverage online. My main point was just that MTB as a whole is much less competitive and more welcoming overall than other cycling disciplines.
I think it may be more that road cycling has a rep on exclusion for anything different than the status quo - they made a book about it, poking fun of it:
Plenty of women around here bike commute, mtb, etc. Women are very vocal in these part on cycling rights and livable cities in general.
There's a women-owned bike shop that caters specifically to people who want to find car replacements in their lives. I'm very proud of them, so I have to share: