That's different to the original question and your original post though. The original point was allowing staff to log in as one user but not as another one. That's not related to technical proficiency or the chance of them making a mistake, that's purely related to whether you trust them or not, in my opinion.
Particularly bearing in mind that just because a super-mod could log in as an admin, it still wouldn't mean they had full access to the acp, as that's separate, as far as I'm aware.