I wouldn't agree there. NIP-05 identifying yourself is free if you have an existing domain. Spammers already utilize domains for spamming and phishing. It would just take 2 seconds to NIP-05 ID all of their bots.
Discussion
A relay know how many users a single relay have, so can whitelist only the "approved" ones (payment powered or connected to other kyc procedures) and those with max 5/10 users (friend and family). If a bot adds 1000 keys to a domain is doomed.
That's correct, but it's also trivial for you to ban the whole domain, so it's a bit of an improvement over naked pubkeys.
ooof! is there a benefit to NIP-05 then?
It's a human readable format for your public key so that you can easily be found, identified, and not mistaken for Jorj@anotherdomain.com.
It's readable for users and a domain can decide to use it as verification.
Also, you can tie multiple NIP-5 to your pubkey and still be found in the search.
Some of the nostrpurple profiles show off their own domain as default in profile.