Yes, because i don't have time to relationshipify (as Freso said) all the releases i import, and also because those informations may disappear from source before they are fully entered as relationships.
I do it mosly for small/unknown bands, because it is often hard to find infos about those bands (especially years after the release of their sole EP...), sometimes relationships are incomplete so i just keep that around to check what is missing later.
Since i lack of time, i always expect another editor to do it But once the annotation data was carefully checked and properly entered it should be removed.
Import scripts don't do it automatically (and shouldn't imho), but i do it a lot for Bandcamp imported releases because Bandcamp annotation is usually worthy (being written by label or artist). Many of those are just what appear on physical releases, i just take care to not copy information not matching the release (for example, CD catno, or packaging info).