White the rise in ads and tracking on TVs is worrying, my main reason for not wanting a 'smart TV' is that they rarely get updates to the OS or pre-installed apps so become a security concern after a while.
I know a few people who have smart TVs from only a few years ago and virtually not of the apps work any more due to the versions of the apps being too old and no updates to the software available.
My current TV is just a dumb display with a miracast dongle connected so I can steam content from my phone to the TV screen. I prefer that as I my phone does get updates to both the OS and apps. Although not happy that the All4 app doesn't support playing on a 'second screen' so won't let you steam from the phone to your TV. But Iplayer, Youtube and Amazon prime video all work fine.