Can't really compare it to a Smart TV or an Apple TV.
Definitely agreed. The common library of the NX was what I believed to be its winning factor when it was understood in 2011 (I believe) with the merging of Nintendo's console and portable development locations.
So in theory, a smart TV could use the common architecture as the Switch Lite, as the Switch, and as a hypothetical Switch TV, but it wouldn't be financially sound. The reason is that a smart TV is currently dominated by Samsung, LG and a handful of others.
But I think Tomatito meant just a Switch TV not a Smart TV, meaning a type of book-sized or ipod-sized device you plug into a TV like the Playstation TV, the Apple TV or the Chromecast.
I am of the same idea as you, so long as the console can play the same games, and perhaps unlock some performance features due to either being more modern (newer tech or less space required), then it is an excellent business case.
It would look a lot more like what we see on PCs, where you can set your graphic settings, only that the settings would be pre-determined by the Switch model itself. (framerate, resolution, anti-aliasing, etc.)
On the topic of sales vs success: you and I agree, success is defined by the quality of the software library and the following a console had. Unfortunately that is not true for the industry. Partners will gravitate around your console so long as it generated profit for all parties involved. And from that vantage point, my hierarchy was true.