I think so too. Path that was mentioned is a very unique and original idea to promote further interaction as an alternative to commenting. It saves a ton of time allowing you more time to explore.

HN is fantastic. It doesn't feel bulky because commenting is integrated with the original idea of the site. In fact, you can't do anything but read and leave comments.

For another site though, like a blog, or a photo sharing site, or even a news article you read online- there aren't a lot of alternative to comments.