[Exmoor]

8k is double the vertical and horizontal resolution of 4k. You can argue that 4k was deceptive, since it switched from measuring the vertical resolution (2160p) to the horizontal, but 8k is just sticking with the established standards.

[clhodapp]

4k was the marketers cashing in a puffery token they'd been carrying for quite a long time by accurately measuring the short side of displays.

They moved to measuring the long side AND exaggerating by rounding up in the same generation, stealing the name of a slightly-better existing standard in the process.

You're right that 8k makes sense so long as you accept 4k, though.

[kuschku]

Well, 4K is called that because when 1080p became common at home, cinemas switched to DCI 4K and suddenly TV manufacturers had to compete with that, so they branded the closest they could get to DCI 4K as their own "UHD 4K".