Often the TV is mounted on the wall above the desk I am working at. So you sit on the bed with your laptop instead and use Miracast and a Microsoft Wireless Display adapter (nice) - but looking near and far is painful as your eyes refocus.
I just find it simpler to have 1 high resolution screen where I can put high def content side-by-side or in quarters on screen.
For now this works, but in 10 years when movies and web pages are 4k by default I'll need an 8k laptop screen (haha)
When I am working I only use one screen, and only one window in the screen, and instead I constantly switch between virtual desktops, to the point where I just think "browser", "editor", "terminal" without even perceiving the keystrokes.
However, for gaming I dream of having one of these ultrawide screens that have the resolution of 3 normal screens side by side. Something quite complicated to have in a laptop, but I have seen some attempts.
Why would you be looking up and down?