I was mildly disappointed that this doesn't appear to be encrypted to my key, since I have Keybase in my profile ;)

The general shape of the argument against this, is you can use age, and avoid the many well-documented problems with the OpenPGP standard.

More people have PGP keys, naturally, but that's a bit of a chicken-and-egg problem. By the time you're messing with cloak-and-dagger stuff like dead drops on public message boards, taking the extra effort to set up to use a better cryptosystem strikes me as relatively minor.