Cause like, it used to be
If you made an online manshooter, you could release it, and just let it be free.
Server code was available to anyone who wanted to host, or pay to get a server. You'd find these weird little places. 2Fort only, bolt action rifles only, hostages only, or little communities on their own. Hampshire Heavies, Furry Pound, or whatever.
But then Xbox centralised, and had a fee.
So now, you can't, or don't, do that. You don't let 'other people' host your games people can connect to. You have to do it yourself.
And that takes money that 'they' aren't paying. So the game costs more, and needs to make money back.
So those little communities, that were fine as they were, are killed. And players have to fork over more cash. Or else.
And I've seen it, I've seen at least one dev say out loud, "please buy the gubbins and skins and themes, or there'll be no game."