One person’s worthless may amuse another (NE). At least for some who want to fly.

I guess most of these sites inhabit people who invest time and strategy for manipulating the visibility and value of the content. I can imagine a frequent visitor would get tired of resurfacing memes. This happens pretty regularly on many sites. A better collaborative filtering as well as use customization may help. I.e. how to not bother those who have seen it, while enabling less frequent visitors and newcomers to see them. I feel guilty telling people who are clearly delighted with some post that so many people saw before. It kind of ruins their fun. On the other hand, it ruins my enjoyment to keep seeing the same old stuff.