I agree. It's just that I see statuses, pictures, tweets, blogs, and the likes that complain about men wantin bones or not wanting curves. I'll share some pics in Gary's thread if I ever find it.
First: Twitter is dominated by some of the stupidest shit ever written, which happens when you discuss a nuanced subject in 140 characters.
Second: When it comes to dating, no complaints of "short preference" or "thin preference" is really relevant. You can't control preferences of other people. If they choose to call you out on being chubby or a pipsqueak, it's pretty clear that they're trying to be an asshole and no relationship could have existed anyways.
Third: But there is a pressure to be thinner just in every day dealings. Many clothes are cheaply designed to fit thin models, making shopping an regular reminder of how you don't measure up to the standard. Supposedly larger women in media are often removed or edited to make them more aesthetically appealing. Women are inundated with images of being the perfect woman, which happens to be a skinny blonde, large rack (though those are mutually exclusive without breast enhancement surgery), thin legs (the better to wear leggings + boots with), long neck, and sloping shoulders.
Basically, the pressure isn't just from one man or woman walking up to a girl and saying "you're fat" (though this happens, it's so blatantly idiotic and assholic it gets called on the spot). It's from images and assumptions about women's bodies. Humans react to seeing images like us, and when we don't see it in media, it's pretty upsetting. The larger you are, though, the pressures increase for both genders. The pressure just grows more intense for women quicker than it does for men. That's when remarks on how you need to go on a diet starts showing up. That's when you barely fit into an airline seat and feel real guilty over invading the seat next to you. That's when losing weight is really difficult, especially once you are past a certain age, and all the distress can paralyze these folks, even to the point of relapsing into eating disorders.
My mom is overweight, but medical problems exacerbate her attempts to lose it. When she has restarted her rowing regime, she has damaged her Achilles tendon, once was bedridden for a month due to compartment syndrome in one leg, and currently has gall stones. As soon as she starts to lose weight, she gets these injuries and health problems that stop her for a month. It's not like she is gorging on MacDs or anything either: we make small balanced meals in-house, usually brocolli + some kind of chicken dish (it's not like we can afford luxurious meals). The end result is that, though she looks 10 years younger than her contemporaries (thanks to the Sami metabolism), she is still fat to all the recruiters she approaches, and thus she is never able to get a job despite how she is more than qualified and her mind is still very sharp (she learned Python with me last year and does a lot of the pitch development for the apps we develop).
tl;dr. Prejudice towards fat people exists, but it's not this ridiculous "he didn't like me because I'm too fat" or "she didn't like me because I'm too short" -- it's something that does actively damage people's lives in their ability to make a living.