Reddit is very geared towards short-term discussion. Top comments on a post are usually from the first couple of hours and posts last less than a day. For long-term discussion traditional forums with chronological posts and threads that get re-bumped to the top are still king.

Meh sounds like Reddit just needs a sort by 'weight' option that sorts by amount of comments.

That's quite different if I'm reading your meaning correctly. That type of system tends to result in the biggest threads staying at the top and getting bigger and bigger while new ones never appear.

Weight can mean anything, freshness of nested posts eg.