You're right, the angular size is the true determining factor. But most people don't have a large enough living room to sit 12' from their TV :) e.g. I've got

You're right, the angular size is the true determining factor. But most people don't have a large enough living room to sit 12' from their TV :) e.g. I've got a 48" UHD TV at 2.5m (8') distance, and a 27" UHD monitor that I use at 60cm distance, and while the TV is beyond the resolution limit of my eyes, the PC monitor isn't.