I should probably have been less specific about who gets to promote things - "site founders" or "a few designated site ambassadors" is mostly what I was thinking, not "anyone who collects enough karma".

If that's the case then I misunderstood you.

I'm not sure how one pursues karma at the expense of quality or clarity

By posting far too often, with the hope that posts will get upvoted more than they get downvoted.