Op used a bad example, the girl imo is not below average and it seems like to most people she is not below average either,
nethertheless, i get the point he is trying to make about girls getting over inflated remarks about their looks online. I have seen it a lot myself with girls who I genuingly beleive most would say are below average.
guys on the whole are a lot thirstier online than in real life. It is so easy to just write a message to a woman, and it requires little to no confidence at all on his part. It is also easier for a man to cheat, and as the girl has no social connections to him it is easier for the man to just pump and dump her and get rid. You can't really do that with a girl in your social circle can you. Also there are some women that a man would like to have sex with but wouldn't take as his girlfriend or walk around in public because he is scared of his image or what his friends might think of her, ....but if he can manage to get her online and none of his circle know about it then that's great for him. A combination of all of the above make online a pretty much ideal place for men to try and get girls. As SO MANY men are using online to try and get girls it is feirecly competitive and men use any means possible to try and secure a female, which often includes giving her false compliments in order for him to appeal more to her.
If a female does not feel great about her apperance and you've got one guy who has convinced her she's beautiful, and he's treating her like a queen and the next guy who's not really being very affectionate then who do you think has the edge? [assuming both guys physically are closely matched looks wise]
This feirce competition drives up a female's market value online to much higher than it is in the real world. Ofline she could be that girl who all the boys in her class ignore or who's never been asked out before, but the moment she steps online and opens a profile on a dating site like plentyoffish she's a SUPERSTAR