I think it depends on the device. If I buy an iPhone, I have the expectation of installing apps on it after purchase, and that necessarily involves a relationship with the app store provider (ie. Apple), not the store I bought the phone from.
With a TV, I suppose it depends on whether I want to install media apps like Prime Video or Netflix on it. I understand that there will be people who don't want that, in which case I agree with you. But others want to be able to run this stuff somehow, whether it's directly on the TV or via some HDMI device like a Chromecast or a Fire Stick. At that point, they _do_ want a relationship with some hardware manufacturer so that the third party app can be delivered to run on the hardware.