A quick search shows that at least some Samsung models have this capability as well.
You might have to agree to a ToS when you first connect to internet. Who knows what privacy you give away signing that.
The update might be a trojan horse containing both the bugfix you need and a new mandatory streaming service tile on the home screen.
I also don't care about tiles on the home screen, because I literally never see the home screen. I always have a device plugged in (and have never connected a TV to the internet for software or other updates, thankfully).
My 2016 OLED LG model had a firmware update that supposedly would halve the max backlight to the point where the TV was unusable. Since I never connected the TV, I was safe from this but as you said I might miss out on some features.
For example, imagine you want to keep a smart TV offline but you also want the latest greatest eARC features over HDMI 2.1; or you want that new Dolby tech to work with your PlayStation 5. That's stuff that came out in the last couple years. Assume it will take the TVs five years to work seemlessly. In the meantime you're gonna need firmware updates. It won't work out of the box. Or maybe it will, but with a noticeable lag.
Whatever smart TV model you're considering, read the patch notes and visit the fan reddits so you know what you're getting into.
An alternative is to get a gaming monitor; however these rarely reach TV screen sizes so if you're looking for 45"+ you're stuck with smart TVs