Generally it is closed to new comments. Nothing was wrong with it but it beats the shit out of the servers to load it. When one of them gets popular it slows down the site to the point pages sometimes don’t load. As far as I know this is used by the caching they use. If a post has 1000 replies memcache will spit out the html file from the cache instead of hitting the database upon every page load to generate the page.
I could be totally wrong. But that is my theory.