I agree that hiding comments would be a better functionality for curators to have, and that it should probably come with a reason and notification to the author of the comment.
Comment authors should probably still have the ability to completely delete their own comments, per EU requirements, though editing with history would be preferable in my view.
Do non-curators currently have the ability to delete others’ comments from their own observations? (Might have to set up a second non-curator account so I can answer questions like that!) If so, that is a scenario that I think merits discussion and debate.