I often ask this as well. Not sure. As a web developer I say the same thing. I think it has to do with TOR. It would become too slow with all the duplicate encryption. I know hey can't use multimedia on these sites on TOR. And even chat rooms fail sometimes. It's shaky technology SSL still makes good sense though just for the order page itself. They can even do server side PGP as well. Why bother with PGP stand alone?