The point is, these charts are (by some measures) out by a significant margin - a lot of people can see much finer detail than 1" of arc (subject to other factors), so they are likely to underestimate the value of having a 4k screen for a given size at their habitual viewing distance.
As I said, even just working on Snellen acuity, you can (if I've got my maths right) add upto 50% to the distances (or reduce screen size accordingly). In terms of simple image perception, it's probably quite a bit more than that.