I myself do not understand how it works, I only know what others who do have said. I once believed along the same lines, but it has been explained to me, by more than 1 person with actual knowledge of how servers, programming, and networking works. People that actually work in IT at server facilities, some at places that host and run other popular games not unlike ffxiv and such that the house wards are not much resources, data, computing resources or hardware required. Number of wards, plots, residential zones isnt the issue, grand scheme the house system as a whole simply does not use much resources, esp if you compare to any other other part of the game. Its not like the house wards are crunching the numbers that say a 24 man raid would in real time. If they were to go infinite housing, some hardware would be needed sure, but its not like for every new ward they must dedicate another whole server rack to it.
If you were to hear this from 1 person who works in this field maybe they are right maybe not. But I have heard from multiple people, who obviously know far more than average folks and they have all said the same thing. And as I understand what they have explained is it truly is not as big an issue as they make it sound. Point is, it isnt a fire breathing dragon, but more of a salamander with anger issues.