...then I don't know how you would say that it can't negatively impact careers.

Not because AD's are looking for advice on some fan site as to who to hire or who to not hire - but because it creates a home for the mob. Rumors can be started and grow from fan sites. Dumb things coaches do - like grabbing a girl's butt at the bar - are suddenly shared far and wide.

You're right that posts won't have an impact on hiring decisions per se. But you're wrong if you don't think fan boards and the social networking aspect of them can't have a negative impact on coaching careers. You spread enough rumors and innuendo - and it certainly grows beyond what's just on the fan board.