I come to Hacker News to read and interact with people about start-ups and hacking related news, not to read jokes. It's not that I don't like to laugh, but there are a lot more popular sites on the web where you can be distracted and read funny stuff than there are where you can have quality discussions on a specific topic with interesting people like Hacker News.

This is rare. While community-oriented sites where you can read jokes/hilarious stuff/trolls are common and all over the place.

So when I want to be distracted, all I have to do is to open a new tab and go to reddit or whatever. HN is a special environment that must be preserved from this kind of stuff in order to keep the focused and quality discussions going on.