Being part of a fandom is a really interesting concept. You share something with thousands, maybe even millions of people and you haven't even met most of them. Among these fandoms, you have a group of elitists, people that have been a fan since the beginning, and sticklers that make up a group of what I like to call butt-hurt fans, and I am sick of them. They ruin everything about the individual experience of whatever fandom they'e a part of (which is essentially anything you could be a fan of).
If this is somehow a foreign concept to you and you have been spared from the butt-hurt (first of all congratulations!), this happens in various forms of media and entertainment. Take Star Wars or the Lord of the Rings for instance. You'll have plenty of people that will tell you that you must watch the movies in the order they were made, which doesn't make sense now that there are movies that take place before the events of the movies that were first made. It doesn't make sense story wise to watch the Lord of the Rings before the Hobbit just because the Lord of the Rings movies were made first. It made sense at the time because those were the movies available to the public, but now you have story events that take place before the first made movies of the series. Just because you watched them as they were made doesn't mean it's necessarily the best way for everyone to experience the fandom.
In music, this phenomenon tends to exist as people complaining that an artist or band had better music earlier in they're career and they "sold out" and "went mainstream" if they try anything different with their sound. These people piss me off. If an artist or band wants to experiment with a new sound and they like, then let them fucking enjoy it. It's not for you to dictate how someone else lives their lives.
Video game butt-hurt fans tend to complain about how a particular game or particular time in a game franchise's history was the best and everything else is created after it is garbage (shout out to the Final Fantasy VII elitists).
So the real question is why these butt-hurt individuals are the way they are. It most likely boils down to them being set in their ways and not being willing to be open to new ideas. They just ruin everything and shit on other people's feelings and experiences. I guess we can only hope that like racists, bigots, homophobes, and corrupt politicians that they'll eventually just die off and the rest of us can survive and rebuild.