[UncleMeat]

Friction. Yes they could use PGP messages. But most people are idiots and use the systems that are available and simple. If somebody needs to think "I've got to go through these extra steps to be an asshole" then they might think twice in the first place.

[def_true_false]

No need for PGP. Using any other messenger that won't give private information out for no reason would be enough.