I know a few people who bought Smart TVs from various manufacturers a few years ago and the Smart functions have one by one been withdrawn as the manufacturers no longer supports them. E.G. YouTube, Netflix and other media player apps. Eventually you are left with a TV with a pretty basic, slow and probably insecure web browser. We got nearly 30 years out of Teletext, nowadays expecting a Smart TV app to be supported for five years is being optimistic.

And will the manufactures open up their TV OSes to allow 3rd parties to offer support. Of course not, but they will helpfully let you know how great their new TVs are.