And 4K streaming is hell on your bandwidth and thus not usable for long by people with a 250 gig per month bandwidth or less in thes tates which is most people, unless you thought Comcast, Charter, etc etc decided to give out free bandwidth and remove thresholds which they didn't. It's also not widely used given that most don't have 4K tv's.
And beginning 4K streams doesn't mean every piece of content is in 4K. To even watch a bluray you're going to be buying a 200-300 dollar Ultra HD Bluray player.
And those TV's you referred to aren't even actual HDR (the specs don't match up) nor do they feature any of the main innovations of TVs in the past years. They're equivalent to 2013 model of 4K tv's essentially the original stuff with a lot of features stripped out. That's like buying a tv on black friday for 300 dollars and thinking you got something not designed from the get go to be cheap. The Samsung one at least is curved so there's that, and I'm not sure why that other one calls itself HDR since the specs don't match up with HDR tvs. Some of these I'd need to research to see why they're misleading.
Why you're looking at 50 inch tv's though is beyond me.