4chan has constraints: There are only 20 pages per board (if I recall correctly) and if a thread does not get new posts and drops from page 20, it's gone foreve

4chan has constraints: There are only 20 pages per board (if I recall correctly) and if a thread does not get new posts and drops from page 20, it's gone forever. Just like the twitter 140 characters limit, 4chan has a history limit. So 4chan perfectly fits in the parent's list of social network like things based on arbitrary contraints