No really though, the guy was a dick to that customer support rep.
"You're not very good at this are you?"
"For customer support, you are terrible at this. Just so you know."
Who talks like that to another human being that's trying to help him?
In the video the rep stated that they disabled that feature because they found that it can introduce performance issues during playback. I'm assuming some minor stuttering here and there.
As to your question, any modern day set is going to scale every bit as well as the Xbox One can. Some sets will add some subtle sharpening filters or even blurring filters but for the most part the picture remains untouched, so therefore the image quality will be identical.
The whole "upscale" term has become a marketing buzzword over the last few years, but it really means absolutely nothing. That's why I'm a bit annoyed with all the backlash. People are freaking out about it and literally have no idea what they're even freaking out about.
Here's a couple good articles on upscaling:
http://www.rtings.com/tv/reviews/by-resolution/4k-ultra-hd-uhd-vs-1080p-full-hd-tvs-and-upscaling-compared
http://www.red.com/learn/red-101/upscaled-1080P-vs-4K