The problem with the software the TV manufacturers put in their TV is that they don't keep it up to date + there is no guarantee that all the streaming services are available for the TV you have bought, it depends on which operating system is used. Of course, with Google's system it's no problem, but then we have Samsung with their Tizen or whatever they call it.
I have a Samsung 65" top model from 2021, and there are several "local" apps I can download for it, which in addition to the fact that it was the top model, the software is stuttering, and poor and impossible to type quickly on .Apple TV is faster, fluid, and has all the apps I need, so I never use my TV's built-in software. But if the TV manufacturers get it under control, I agree - then Apple TV will be redundant.
Maybe Apple should make a TV interface for the TV manufacturers, just as they make CarPlay for the cars.