To add to that, using "nostr:nip05:user@domain" doesn't require any context. It says what it is.
Using "user@domain" requires context. You have to know external to the data that this is a nip05 address. In which case you already know that it is not an email address.
A user only confuses it with an email address if the context isn't obvious. And if the context isn't obvious, then the data should specify the context.