It seems to me there's 2 reasons some people view it this way:
- It's hard to use for normal people, it's a lot easier to hand someone Signal
- It allows cipher suite changes, some of which may be weak
Basically, for the purposes you're talking about, ease of use isn't a major concern, but the second one is. A dead simple Ed25519-only signing tool would be viewed as better... does such a thing exist? Certainly it's fairly easy to create one using NaCl or even the reference implementation, but nothing has the popularity of GPG.
Somewhat offtopic, but I'd love something like gnupg to support deterministic key generation, similar to what BIP39 did for crypto. I currently generate keys on an offline computer, back them up to a usb driver, and the copy the keys to yubikeys. It works, but it's a PITA, and I'm always worried that I'll lose my backups despite going through a lot of effort to keep them.
Deterministic key generation is one thing crypto has gotten right.
"crypto" is not short for "cryptocurrency", which is what I assume you mean. For many people it is short for "cryptography", and if read as such, makes your comment very confusing.
It's short for both at this point. The cryptography community doesn't get to dictate the meaning of ambiguous abbreviations, despite their frustrations. I agree that its confusing in context, though.
It's pretty handy, but doing it for RSA and other crypto systems which rely on large primes is much harder than doing it for crypto systems which can basically use random numbers with a few safety checks just due to the nature of key derivation functions. It is possible though, I seem to remember seeing a paper on it a while back and it should be entirely achievable to do something simple like seed the rng you use for generating RSA keys with an explicit value like that.
For basic signing and verifying purposes I believe Electrum and a few other clients actually include functionality for this which could be used as an alternative to PGP.
- It's hard to use for normal people, it's a lot easier to hand someone Signal
- It allows cipher suite changes, some of which may be weak
Basically, for the purposes you're talking about, ease of use isn't a major concern, but the second one is. A dead simple Ed25519-only signing tool would be viewed as better... does such a thing exist? Certainly it's fairly easy to create one using NaCl or even the reference implementation, but nothing has the popularity of GPG.