Shut down of Xbox 360 Halo

I know this is late news but soon at the end of this year all xbox 360 halo titles will soon lose all multiplayer support. I always knew it was going to happen sometime but its sad to see it go. There's only real one problem with it, why do they have to? Last time I remember (I could be wrong) the way how halo multiplayer works is that someone hosts the game, not a server itself. I really don't see the point of shutting down the services if its the players that host the multiplayer and not the company itself. I know I could be completely wrong but I really don't see the point of them doing this, especially when this will most likely be the year halo will blow up and people will flock into the franchise as new fans and want to play the series as a whole. (MCC exists I know but it fails to really bring a true replicated experience to playing these games.)