I’ve long encouraged people to at least make a GPG key, even for reasons other than encryption. But that doesn’t necessarily mean they told me about it.
That’s the role keyservers are supposed to play. You put your public key up there, so that others can query the public half of your key. It is, well, the public half.
But if I have hundreds of contacts and have no idea if any of them have registered their key… well, let’s say that would take forever with the web interface.
So I made a bash program that takes your exported address book (in VCF format) and queries several keyservers in order until it finds a match. If it does find a match, the public key will be added to your gpg keyring.