So, you would prioritise comments from those who on average made upvoted comments?
You could (relatively) easily, implement Pagerank but use votes instead of links. This would make people who have lots of (quality) upvotes have more weight.
Whether it would improve the quality of the comment sections is an interesting question. I'd be interested to see that tested somewhere ...
I've been toying with this idea. My go to would be to do a pagerank on the vote graph. The intrinsic quality of a webpage was transitive enough to make Google win the search engine war; surely people can be viewed as websites that have links indicating quality to other commenters: HN accounts and votes to someone else's comments.
If only HN could release the vote/down dataset...
That could be a privacy violation. Maybe they could do it themselves, or try to disclose it to select trustworthy parties.
Maybe they're doing it internally and they're keeping it to themselves. After all, YC is in the business of detecting precisely individuals that are capable of articulating high quality ideas.