On a perfect team, where everyone is great at time management, honest about productivity, has superb communication skills, and is enthusiastic/loves their tasks, yes, scrum is dumb. For but for the rest of us, the scrum master handles all the unpleasant organizational crap for the team, and thank god for them.
Maybe not _need_ it, but it can help in a lot of cases. Though I have seen some cases of active resistance coming from participants, in which case toxic co-workers can really make the experience miserable.