"20 in 20" sounds like you wanted a winning headline (which I guess is the case)
Please stop scolding the user for trying something out of the norm. It just means one will have to take a bit more effort to go back the first page of http://news.ycombinator.com/newest (click the more link... some more).
You can also tell the user that comments hold more value for a person than posting links.
It is like twitter for some people at first you try to mimic the big guys as fast and as abundant as possible but after a while you "get" the system.
Give the user some time o0. These guidelines are taken as advice no? After all this is just an experiment. Stop smothering the small guys, we are people too :)