The biggest issue I have is that timcliff brought this up as a way to combat abuse by those who are self voting useless content. It isn't a solution to that problem. Logically, when their posts start getting down voted, they'll do the same to others. And then it becomes a measure of who has more vests.

This is what is supposed to be self-regulating. I can agree that there might still be good to have some coded limits to this, but they are not all that easy to actually impose because they have to be done through incentives somehow. Not just blocking a feature.

Perhaps down voting that only impacts a post when it has more downvotes than upvotes, or is above a certain threshold would work better.

I stand corrected. Maybe you made an error in your writing here. But limits like these can't certainly work to mitigate at least part of the problem, because they can't be avoided by buying votes etc.