[claudiawerner]

The point of imageboard-style thread pruning isn't to erase the content from the Internet (after all, there's a small archive for every board on 4chan on 4chan itself and much larger ones elsewhere on the net) but rather it's to keep the content fresh and encourage new material rather than ruminating on old material - it's much easier to notice new posts when threads are small, instead of scrolling through 1000 posts that most people never bother to read. HN deals with it with the fact that if you comment on a HN post two weeks after it was posted then it won't bump the thread.