What happened to games having a multitude of servers? [closed]

There are multiple impacts here, but three major ones are certainly maintainability, centralization, and monetization.

With private servers, running live services and monetizing them becomes muddy and difficult. Largely because a server is used to confirm that the skin/upgrade/weapon/character that you are playing has in fact been purchased by you. If you are connected to a private server, it can simple say yes to all those request, and suddenly everything has been unlocked with no purchase.

Centralization is another point. Many games now a days have moved to a system where you have a profile that can level up and leveling up this profile will unlock new in-game mechanics/maps/weapons/characters, which means that a centralized server to handle everything is required and as such it makes sense to handle the game server as well. (This again also refers to the previous issue with private servers)

Maintainability is probably a big factor as well. Private servers requires players maintain them, this isn't very ideal for a company for two major reasons. First if the game is doing really well, they can't force the private servers to expand capacity and it can cause a surge of players to leave or even outright kill a game. The opposite is also true. They can't force the private servers to downscale when a new edition of the game is released. While the last practice is scummy, it is certainly something game companies consider..

All in all, the control that comes with running your own servers (And only you running them) is really enticing for a lot of companies, so to them it seems like an obvious direction to go.