> but that also means they're hard to remember

Nobody remembers domain names either, that's what we have search engines for. The point of public keys is that they give the user something they own completely themselves and that their peers can verify. All the human-readable stuff can be implemented on top of that, e.g. if you wanna use domain names, put the public key into your DNS record. But you aren't forced to use domain names, you can send your keys around by mail if you prefer or put them in your Instgram bio.

The most important part here is that this works towards a "Web as data structure". Everything that is based around domain names will fall apart in a few months or years when those domain names expire, links go dead constantly. Everything that is build around crypto can last forever, as the storage location becomes irrelevant.

We already saw the benefits of this approach back with Usenet, where large parts of it could be reconstructed from random backup tapes, since everything was held together by globally unique message ids. Usenet didn't use crypto for this, but just depended on users behaving nicely, so that approach wouldn't work today, but it could be replicated with public key crypto in a very similar and more robust way.