Online Gametype Server

Hello All Gamers, Why the creators of bungie or 343 industries add in new gametypes in the online playlist of all halo series multiplayer and then suddenly within that month that specific new gametype is removed from online matching playlist? can’t you just keep the playlist in the game?

These are called rotational playlists. They swap and change the gametypes to stop the game being stale and boring by changing them every once in a while.