Hi edw519, Mainly that Hacker News isn't a forum. The format makes discussions here ephemeral. Hacker news is a niche site for posts of general-interest to that niche.

A forum is topical, so narrow interest posts are channeled into topic areas. In a forum you might have a topic "Co-Founders Wanted" but only people interested in being/finding co-founders at a given time would read and post in that topic. If Hacker news was mainly narrow-interest postings (ever seen this bug?, co-founder wanted) the signal to noise ratio would degrade.

A Hacker News Forum would be great because 1-this community is great and 2-I could browse topics I'm interested in at the point in time they're of interest to me.