it also clutters the server (relay). disk space is a scarce resource as much as attention is.
https://github.com/nostr-protocol/nips/blob/fd914c600fd590e6188534cd7555116da7855503/59.md
If the relay can't identify the sender how can the relay block senders to protect itself from spam.
Discussion
You can have a deal with your users to delete GiftWraps after some time to declutter. But that is between the replay operator and the user. The same clutter can happen with DMs. So this is not an issue of the new method.