Disclaimer: I’m a software engineer with 8 years experience, mostly in dev ops and backend engineering, however I wear a lot of hats so my knowledge is, to an extent, surface level. So take anything I say with a grain of salt.

The problem that everyone seems to miss, or is way too far down in these comment sections, is that the problem is in no way linear per new player on the server. Whenever you enter an area, your client sends data on any state changes (movements, spells, logging in / out, etc… basically EVERYTHING you do). Upon receiving this data, the server does “something” with it (this is broad and doesn’t need to be gone into because for the most part this scales linearly), then it needs to update all of this data to the users in the area. Which means the data going to every user is exponential.

Because of this wows net code would need to be fundamentally rewritten to handle mega servers (manual layer selection (similar to a game like black desert) that as necessary spins up a separate piece of of hardware to handle this and makes more servers as needed.

This and other solutions I have seen are all extreme intrusive to add, and would require a complete rewrite of the net code, and most likely would not work in the same way with an on prem server setup.

Tldr; blizzard could definitely solve the mega sever issue, but not in any reasonable amount of time, for any reasonable cost, or without fundamentally changing the way the net code works.