I agree, NIP-5 has nothing to do with verification.
I think a (decentralized) verification system on Nostr is possible, but it would have nothing whatsoever to do with NIP-5.
Indeed, NIP-05 isn't meant at all as a verification system.
nostr:naddr1qvzqqqr4gupzq5455pmtewaacws6a73hxkqkea6fjwcm3keq9vqu3q7930nl4k9aqy88wumn8ghj7mn0wvhxcmmv9uqpymnfwqcr2ttfwvkkumm594mx2unfvcyv4z98