I use all those types of cryptography too, but NFTs provide additional features.
The special thing about NFTs is that they're securely transferable on a public ledger, which isn't really the case with client certificates or ssh keys.
Let's say I buy a ticket to a show as an NFT and I want to give it to you. I can simply send it to your wallet address, and now you own it and can prove you do at admission time.
If I resell the ticket to you at a premium, perhaps the performer gets an additional cut to help them capture some of the resale value and reduce scalping.
I'm not sure how you'd do this with SSH keys or private certificates, but I think you would end up needing some kind of registration/directory/ledger service, and then you've just invented cryptocurrency again.
The special thing about NFTs is that they're securely transferable on a public ledger, which isn't really the case with client certificates or ssh keys.
Let's say I buy a ticket to a show as an NFT and I want to give it to you. I can simply send it to your wallet address, and now you own it and can prove you do at admission time.
If I resell the ticket to you at a premium, perhaps the performer gets an additional cut to help them capture some of the resale value and reduce scalping.
I'm not sure how you'd do this with SSH keys or private certificates, but I think you would end up needing some kind of registration/directory/ledger service, and then you've just invented cryptocurrency again.