The way I understand, the difference is “I think this may be a problem” vs. “I have decided this is a problem”, where if enough think it “may be a problem” it then becomes hidden.
From my experience only rarely, if ever, do hidden posts get edited into being acceptable by the member that posted. So I doubt many would be upset if they discovered their post was wrongly hidden. Just the same, I think that group consensus is safer than solo judgement. Depending on how trusted the members offered the ability are of course.
And it depends on the problem type too. IMHO allowing spam to be hidden is more reasonable than hiding an off-topic.