Why not? These are the same people who download full-length movies and cds, because they don't feel like paying for them. There are communities in live journal for that, too. Then, when they get caught, they play victim. It's sickening. And anyone who has a bad word to say at Peter, as though he did ANYTHING wrong can fuck off.
I don't think they necessarily are 'the same people'. I mean, probably there's some overlap, but I don't think it's the same philosophy necessarily. People who want full comics for free can, presumably, get them from the same kinds of places as people get free movies and cds. That's not really the desire to which s_d catered. Like Spaceman Spiff, I read s_d a fair bit. I went for the fan commentary and reviews though. If something came up that I liked, I'd go out and buy the comic. I love s_d, and I'm the embarrassing square who even paid for her copy of Photoshop and feels guilty about borrowing the same book too often from the library.
There are entitled jerks everywhere, of course. But there are also plenty of fans who are fastidious about paying creators for their canon fixes, while also wanting to muck around with other fans in spaces like s_d.