It's not just about the resolution, it's about physical area.
My plan is to buy a 65" or 75" 8k TV and use it as computer monitor. I'll have a screen that is as big as my desk.
A display of that size will allow me to have my IDE, source control, terminals, log files, the app that I'm developing, my email, the CI dashboard all visible at the same time.
Of course I'll mainly use the bottom center of the huge display, but I think it will be a completely different experience when you no longer have to cmd-tab between apps but can just glance up/left/right to see what's going on.
What you want is a curved ultrawide monitor like the Samsung Odyssey G9. I have one of them (49"). The curve is critical, because it allows the entire surface of the monitor to be basically the same distance from your eyes... meaning you can just glance to the side to use that app you placed in the corner. I have good vision but even for me a non-curved 49" ultrawide is unpleasant to use because the edges and corners are so far from your eyes. The 49" size is also large enough that it almost completely fills your field of view when seated normally.
A 75" TV is going to cost you a lot of money for a very ineffective display. It's so large that you'll probably have to physically move several feet to see the edges, meaning that realistically only about half the screen is usable.
The ultra-wide monitors sound nice, but they don't really offer that much space; it's basically just two 27" displays side by side.
I currently have two 27" and three 24" displays on my desk. I already physically move to focus on specific tasks (eg. I have email on a vertical monitor on the side, so when answering emails I'll roll over a bit to the side with my chair).
With a TV, I could have one big seamless area instead.
The one thing that does worry me about the TV is the lack of tilt at the top -- everything in the top half of the monitor will be hard to see because of the angle.
When I work with pen and paper, my entire desk is full of stuff, a dozen sheets and books, printouts and diagrams, all visible at a glance.
I don't see why I should limit myself to a much smaller area when working digitally.
Normal desktop monitor viewing distance (at the back of an 80cm deep desk), but I'm going to use it at 1x scaling. 65" will probably make the text too small -- I think the ideal resolution would be an ~80" display, but 75" and 85" TVs would be wider than my desk.
GP didn't mention degrading retinas, just age. I'm over 50 and need glasses but, while acknowledging that life is a one-way journey, I just don't like people talking like ageing is necessarily this slide into decrepitude after 40.
The vast, vast majority of people in their 40s (wearing appropriate glasses if necessary) can tell the difference between an average monitor and a 4K display, which is the context of their comment.
