Yes, women actually write things like that in their profiles. Are the pickings so plentiful on dating sites that women can now afford to disqualify men because of the baseball teams they support? Personally, I've never dated a woman who knew the difference between a touchdown and a home run, but apparently there are die hard Yankee fans out there that won't date me simply because I like the Mets. If you're that obsessed with a sports team that you won't date an opposing team's fan, dating probably shouldn't be your first priority. Getting a refill for your Thorazine prescription should.
I suppose many of these women pretend to be sports fans because they think that's what guys want. It's not. I don't know of any guys who sit around wishing they could meet a woman who knows how to figure out a batter's slugging percentage.
Maybe they think they're being cute. They're not.
Regardless of the motivation, though, why potentially alienate a guy over something so arbitrary as his loyalty to a baseball team? Aren't there better things over which to disqualify a man? Like say...his name? I actually read the profile of a woman who refuses to date guys named Michael. She once had a bad experience with a guy named Michael, and she's now imposing a ban on all men with that name...and that's actually the least psychotic portion of her profile.
I think I have more respect for the woman who wrote, "I'm hot so don't contact me if you're ugly." There's at least some logic in that thinking. And, hey, if she doesn't respond to my email, at least I'll know it's not because I'm a Met fan.