That was what a lot of people used to say before 1080p content was ubiquitous. That the difference between 720p and 1080p wasn't that huge.
A few years from now people won't be able to stomach anything below 4K.
Ă„hm... the people that said that to 720 partially still dont see the big difference between 720p and 1080. Just look up how many tv stations are still broadcasting in 720...
It depends on a lot of factors:
Eye sight, view distance, display size (and display tech...), contrast, if the room is bright or dark...
There are some subtle differences even if you dont see the resolution as distinct pixels (contrast perception,...), but overall most people wont realize half the time if a signal will be 1080 or 4k if you change the signal to their tv at a "reasonable viewing distance".
Its quite simple: Resolution of the eye is aproximately 1 arcmin (60 cpd), if your resolution aproximates 1.5 arcmin, you are golden. The eye physically cant resolve that high.
And depending on viewing distance, some already have that with their 1080p TV since they are sitting far away...
Im currently using a 4k 27" monitor. Not because it is that much better for gaming (only a switch and a 13" notebook), but because for programming with a distance of 2-3 feet i have a huge benefit.
80% of people here dont see de benefit at this size in 4k and advertize 1440@144 displays.
High resolution is importaint for still images and text (so, pc work). But how much of your gaming time are you looking at still images? not much.
Its the same with high quality audio:
shure, its technically better. And while the average person definitely can hear the difference between radio or a 128kb/s mp3 compared to a cd... with blind tests most people could not hear the difference between 192kb/s mp3s and cds.
For consumer displays, 4k is more or less the upper limit of what makes sense. Shure, you could buy a 75" TV, but how many really have the space for that? of a good projector in 4k, that you pay 3k$?
If you have a more reasonable 50" tv and are sitting 10 feet from it, for moving images...yeah, there wont be much difference.
To make the audio comparison:
<128kb/s doesnt sound great, but you get the gist. Usefull for special usecases (restricted signals, simple text recordings or jingles,... like old pixel games, or videos where you dont care for the visual quality but for the context. Like watching interviews/podcasts/etc on youtube on celular data @ 144p...)
I would say while 128kb/s mp3s are 720p, you can listen to it, its okay, great for background consumption.
1080 is 160 kb/s where it sounds good to great.
4k would be 192kb/s where most people are having a hard time discerning the difference if they are not focused on the details, and 8k would be 320kb/s mp3/FLAC. Something for true enthusiasts, but not nececarry in any way to appreciate the medium and the content.
(>8k would be "studio master tapes", since nobody needs that, except maybe huge projections...)
By the way: there is a reason why smartphone makers have gone back to making high end phones with 1080 screens... cheaper, use less energy (longer battery), and even tech enthusiast channels on youtube say "they dont really see a big difference".