Not being able to up/downvote comments was a major turn off. They'd throw whooping 5 voting credits in your direction every few weeks, but that only served to a

Not being able to up/downvote comments was a major turn off. They'd throw whooping 5 voting credits in your direction every few weeks, but that only served to antagonize people even more. They tried to fix that by giving away meta-mod rights (to let you decide if other people's up/downvoting were fair), but again that wasn't what was needed. So as soon as HN had enough momentum and started to become a viable alternative people left in droves. It was a true exodus. Not really sure who stayed there...