I was about to suggest the exact same thing, so I totally agree with the CAPTCHA solution. And maybe having a (daily?) article submission limit per user at the

I was about to suggest the exact same thing, so I totally agree with the CAPTCHA solution. And maybe having a (daily?) article submission limit per user at the same time would keep people from submitting articles just for the sake of it. It crossed my mind allowing users with more karma to have higher submission limits, but that might aswel be gamed at some point by some users. So perhaps the best thing is having a CAPTCHA to avoid bot submissions and some kind of limit to avoid manual spamming. Truth is, HN article quality has been slowly declining in the last few months and we keep seeing the same sources over and over again on the front page.