In life people will generally see something, laugh or get amused, then move on. This is understandable. There is generally a period of time that will go by that you can then refresh people with that item. Some will hate it because they will say they have seen it before and can't believe they are bringing it back.
Others will not have seen this item because they are younger or not from that area. On the internet you can see this well in communities were content is posted by the community.
An online community is interesting because it seems as if time is in hyper-drive. You can miss an entire evolution step in less than 24 hours. Some one part of the site may go away, people get pissed, they bring it back all in 24 hours. Sometimes the items last longer and people do get to see it if they visit at least once a day. HOWEVER some people will be super casual users and not come very often and wonder what people are talking about. Sometimes they don't even get there to hear people talk about it but they see it later when someone reposts the item because they themselves have never seen it and thought it was awesome to show off.
In society this happens with products every so many years. The older generations market gets flooded with a particular toy or what not and cannot then sell anymore. So then when the whole new generation comes in they can re-market it to the new generation. The older people may be confused as to why they brought the item back because they had seen it for so long before, yet their children will be like, "Wow, dad can you buy me this awesome toy?".
This is completely natural for human nature. We all have a different perspective on things as we have either not experienced something or have experienced something.
Some people just have a super idealistic personality where they feel that when they have experienced something that it is not OK to then happen again if they don't want to see it again. They completely disregard everyone elses feelings.
The hatred of reposts, redos, etc. is most likely similar to any other pet peeve that seems irrational. Things like yelling at the TV, yelling at other drivers when your windows are all rolled up and they can't even hear you, etc.
So when you see these people you can help yourself and kill YOUR pet peeve of THEIR pet peeve. You can realize that they are just frustrated and laugh at the silly redo rage. This way you can at least relieve your stress and not be pissy because of them being pissy.
Things can be much easier in life if you realize that people tend to be petty and hilarious when doing so.