What if one person's idea of 'reasonable' isn't the same as someone elses'? They could be 'zapped' for downmodding not because the disagree, but becasue they do

What if one person's idea of 'reasonable' isn't the same as someone elses'? They could be 'zapped' for downmodding not because the disagree, but becasue they don't believe the comment adds anything to the discussion. That's exactly why we have modding in the first place: so all of us can benefit from the collective filtering of the good comments. If it was a completely unsubjective judgment then having a single moderator would be the solution.