PGP has 50,000 users counting by the keyservers, Tor has two million daily users. I don't think that's reasonable that 97.5% of the people who care enough to use Tor haven't used PGP in years. (Yes, that's a back-of-the-envelope calculation.)

My conclusion from that disparity is that PGP is broken by a flank attack: Its usability is so bad that the encryption goes unused.