You're probably right about the weighting. Anecdotally, again, I think most posts here get either upvotes or downvotes but not many of both. If so, the weighting doesn't much matter. That's a sign that the community has a consistent idea of what it wants and doesn't want. The guidelines here support that. I suspect these numbers would be very different at Reddit. Where this doesn't hold, the handling of "controversial" posts becomes more important. If Reddit just killed controversial posts, how would Reddit change over time? I guess it would get a bit less noisy. (Disregarding the potential for abuse. Obviously Reddit cannot really disregard this problem given their user base, so I realize I'm oversimplifying.)

A post at (+1,-0) is a very different thing from a post at (+6,-5) and treating these equivalently will tend to favor heat over light.