The real absurdity of 2k/4k/etc is that those refer to approximate horizontal pixel counts, when "lines" (vertical pixel count) such as 480/525/1080/etc has been the typical dimension for such a long time. Why the switch? In the 16:9 world, ~2k horizontal is close enough to ~1k (1080) vertical, and ~4k horizontal is close enough to ~2k (2160) vertical, etc. so it can't be that the horizontal numbers round to the nearest k better than the vertical numbers.