Your TV does _tons_ of processing to display SDR content (24fps pulldown if the panel isn't 120hz, motion/judder compensation, "sport mode" and a bajillion of other things, and these get orders of magnitude more complicated when HDR gets into the picture (tone mapping is a Whole Thing!), and that's before we've even started talking about compensating for physical quirks of different panel types.
And this isn't the "motion smoothing" (though it also does that!) kinda processing, which purists will want to disable. Some of those are configurable and can (should) be turned off, but many of those are just what's required to make the image look good, without messing with the "creative intent" or whatever.
OLED displays need to have another layer of processing applied to make sure they don't burn-in; there's another layer of logic when displaying near-black content (turning a pixel takes more time than switching a color; sometimes you don't want to turn off a pixel for a single frame if it's gonna be lit up in the next again, etc, etc.). There are other consideration for other panel types, you also have to worry about heat and bajillion other things.
This is why you won't get a high-quality, dumb TVs.
You just physically can't make a high-end TV without putting a powerful SoC in it. And if you're doing that, you might as well install an Android on it for a nice OOTB experience.
Intersection between people who want the best picture quality you can get, and who are very... particular about what software runs on their TVs (and aren't satisfied with "just don't connect it to Wi-Fi") is not big enough to make a product for, to put it very delicately.
People who don't care about picture quality _might_ buy "dumb" TVs, but margins on those are so much smaller, nobody cares.