Long term keys are almost never what you want. If you keep using a key, it eventually gets exposed. You want the blast radius of a compromise to be as small as possible, and, just as importantly, you don’t want users to hesitate even for a moment at the thought of rolling a new key if there’s any concern at all about the safety of their current key.

PGP begs users to keep a practically-forever root key tied to their identity. It does this by making keys annoying to generate and exchange, by encouraging “key signing parties”, and by creating a “web of trust” where keys depend on other keys.

We can’t say this any better than Ted Unangst: There was a PGP usability study conducted a few years ago where a group of technical people were placed in a room with a computer and asked to set up PGP. Two hours later, they were never seen or heard from again.

There are, as you’re about to see, lots of problems with PGP. Fortunately, if you’re not morbidly curious, there’s a simple meta-problem with it: it was designed in the 1990s, before serious modern cryptography. No competent crypto engineer would design a system that looked like PGP today, nor tolerate most of its defects in any other design. Serious cryptographers have largely given up on PGP and don’t spend much time publishing on it anymore (with a notable exception). Well-understood problems in PGP have gone unaddressed for over a decade because of this.

In 1997, at the dawn of the internet’s potential, the working hypothesis for privacy enhancing technology was simple: we’d develop really flexible power tools for ourselves, and then teach everyone to be like us. Everyone sending messages to each other would just need to understand the basic principles of cryptography. GPG is the result of that origin story. Instead of developing opinionated software with a simple interface, GPG was written to be as powerful and flexible as possible. It’s up to the user whether the underlying cipher is SERPENT or IDEA or TwoFish. The GnuPG man page is over sixteen thousand words long; for comparison, the novel Fahrenheit 451 is only 40k words. Worse, it turns out that nobody else found all this stuff to be fascinating. Even though GPG has been around for almost 20 years, there are only ~50,000 keys in the “strong set,” and less than 4 million keys have ever been published to the SKS keyserver pool ever. By today’s standards, that’s a shockingly small user base for a month of activity, much less 20 years.

Then, there's the UX problem. Easy crippling mistakes. Messy keyserver listings from years ago. "I can't read this email on my phone". "Or on the laptop, I left the keys I never use on the other machine".