Hopefully I'm not derailling the discussion too much but, while on the subject of alternatives to passwords, I've long wondered why ssh public/private key pairs

Hopefully I'm not derailling the discussion too much but, while on the subject of alternatives to passwords, I've long wondered why ssh public/private key pairs are not used for logging into websites? I use ssh with public/private keys to log in to various servers I host websites on, to connect to git repos, as well as to connect to 'things'on my local network, such as RaspberryPis, etc. It's about as painless as you can get and is very secure. So why is this method not used more widely on the web in general? I realise that currently it's not very user-friendly to create and upload ssh keys, as we have to do it from the command line. But I wouldn't have thought it beyond the wit of software developers to put an idiot-proof GUI on top of the procedure. Then, whenever we need to create a login for somewhere, we'd just upload our public key and we'd have passwordless login. It seems so obvious, there must be a practical reason it isn't done. So, what is it?