The 1st quibble is that message boards are not predominately populated by "old men." Some of us live in our mom's basements after all.
The more salient quibble is that the schools that recruit "against" us do point out the negativity on ND's fan sites (I was personally told of a very specific examples by the parent of an ND recruit) to recruits. The other fact is that both parents and high school coaches also do pay attention to fan sites.
It cuts both ways and while I certainly couldn't cite a recruit has made a choice based on message board content, they do pay attention to the 'aura' or 'feel' around a school and a program and fan sites (and now Twitter and Instagram) help create part of that feel.