Botmasters like situations where they can hide offline and buy bots blue checkmarks with stolen credit cards.
But if you were to actually succeed in making key signing parties a more common thing that people used to test for human-ness, and that test was tied to meaningful things online, it would both become easier to fake and more valuable to fake.
If you look at my key, you will find it is heavily connected to the keys that sign most linux distributions, bitcoin, and commits to the Linux kernel today.
If those 5444 linked identities that long pre-date AI are colluded to create a fake me and fake people that signed people who signed me over the last 25 years, and got those fake fingerprints in the keychains of every distro and got matching fingerprints on thousands of privately owned sites, we indeed have serious problems.
PGP does not need mass adoption to function, but with solutions like keyoxide offering a more accessible trust onramp, it is there for anyone that wants to self certify and take control of their own identity today, and get signed by trusted community members tomorrow at a conference.