So, why let newer users vote at all? They can't downvote either, so there ought to be a karma threshold for voting as well, too. Then you would have to own some credibility (=karma) before you can begin to affect the site's future.
You get karma by posting good links and writing good comments. Who decides what's "good"? Those who have karma, of course! Back to the circle of insiders! So, you ought to gain karma normally if a high-karma user votes up your submission or comment. If lots of low-karma users do that you might get a tiny bit of karma but no more. If only few low-karma users do that you get nothing.
That should at least give most of the control to users with high karma. Note: I'm not entirely sure how HN works for beginners these days, so some of the above might already be in effect.