The thing is, I want smart features, I just don't want those smart features to be tied to the display. A separate box allows more consumer choice, which is generally a better experience. Easily flashable firmware would be an acceptable alternative for the same reason.

I'd be happy with a setup box giving me the ability to add apps for streaming services or whatever, but I don't want that STB spying on my either. I feel like even if all TVs were dumb monitors we'd just be moving the real problem of insane levels of data collection and spying to another device. We need strong regulation with real teeth to prevent the spying at which point all of our devices should be protected.

A separate box allows more consumer choice, which is generally a better experience.

In the life of my last TV (10+ yrs), I've had to switch out that separate box three times. It would have sucked & been way more expensive to have had to replace the TV each time.

Firmware can be updated, sure, but there's the risk of some internal component failing. There's the risk of the services I want to use not being compatible. I'd also prefer to use an operating system I'm familiar with, because, well, I'm familiar with it, rather than some custom firmware from a TV company whose goal is to sell your data, not make a good user experience...

Of course, this ties back to the enshittification of the Internet. Every company is trying to be a data broker now though, because they see it as free passive income.

Hi-fi and AV enthusiasts have known that "separates" is where it's at since the beginning. Unfortunately it's such a small segment compared to mass market junk "content" devices and it's only shrinking as more people are seduced by the convenience of the shit stuff.