Certainly not as easy as you probably think.
It's not only a server issue, but the game itself doesn't probably like the idea of having that many users inside the same map.
To be fair, we could blame both the server, game and even the users themselves.
The reason why plains is problematic is because it's simply the most populated map in the whole game, the reason why it's the most populated map in the game is because of lack of maps for players to go to that has some sort of interesting environment. This is nothing that would happen, but if users started going into more other maps and not making fluorite the bottleneck no characters would get stuck there, but it's not really easy done since users choose to go there since it's the biggest map that has the most content in it.
The map should've been replaced long ago with something smaller and more maps should exist in the game to be fair, that would solve quite a few issues I believe.
