Here is one popular blog with a simple open voting system: http://www.preposterousuniverse.com/blog

That has voting but it doesn't seem to have threaded comments. That means switching to that plugin would break all the existing comment threads.

As I said, Scott is not interested in improving the commenting system,

I would guess that the main issue is that he doesn't want to do work to improve it.

Arguing what's an improvement also isn't easy.

If I look at the blogs of influential people who do put effort into it, I don't see that they all use a comment solution that Scott refuses to use.