It's a reasonable argument though people often simplify it. Player Housing is asking for a massive amount of developer time from a lot of teams (The zone team for basic setting if it's more than an interior; the team that does general buildings, doodads, world objects, etc. for hundreds of new assets in addition to their regular duties making stuff for new zones/instances/raids; the primary systems teams which has to code a whole bunch of new stuff for moving around and placing things and the systems to save and load an elaborate instanced collection of objects per character; the profession team to set up potentially whole new professions for it as well as the materials and like (which also require their own new world objects and stuff); the UI/Interface team who has to build the whole front end, tooltips for all the items, etc.)
It's one thing when you are doing that work in the background during the initial making of the game, or when it's the dedicated content update, but when you're asking for what is realistically as much content as a major content patch from every team but the quest and dungeons ones, in addition to the regular content that has to be put in a given expansion it's a lot.
The engine was never built with that sort of thing in mind. It's one thing to have something like Garrisons where you have a small set of plots that can accept a handful of building types, it's another thing entirely to have a satisfying housing system where you have hundreds of different objects in a region the player can much more freely place and rotate.
To be meaningful it also has to see constant support, which means some of those teams (not the UI or Systems, which are foundational, but the art, profession, etc.) have to continue to every patch dedicate additional time to making new items and things for the housing system next to whatever stuff they make for the actual patch.
Additionally this elaborate system with a ton of required work is a system that inherently encourages players to spend a large amount of time isolated in their own little instanced world building stuff just right, rather than out populating the world and running around. Sure, there are parts of it you can use to get people out into the world (gathering materials or doing activities for various resources or currencies) but those are activities that people are doing anyway for main system resources and materials, so it's not like you're increasing the amount of traffic in the world, you're just getting the normal gathering and running around farming and shit, but with the added caveat that when finished, instead of even running around in circles in Oribos, that person then hearths and completely removes themselves from the world.
I love building shit in games. I grew up playing build servers in Starsiege: Tribes/Tribes 2, which were like a prototype G-mod. I love adding big mod houses to Elder Scrolls games and filling it with neat weapons and armor and random books and objects to make it feel live a real home. I just don't think it's a great fit for wow. Like if we are talking hypothetical, elaborate systems that involve a ton of dev work, I'd rather see that time and effort go to some sort of world system. Revamp cities/towns to involve server community input with building projects decided collectively/build decay with repeatable resource turn-ins and quests for maintenance, etc. Get people doing shit together out in the world, not hiding away in a personal instance getting their furniture just right.
I'd rather spend time grinding Drust in Ardenweald to keep some constantly-draining zone-spanning anima slipstream active that players can enter for double mount speed than grinding drust to get the mats for nice table in my house my friends will see a couple times.