You are not missing anything.

It's worth remembering that most films made in the past two decades have been mastered at 2K, most films are distributed to cinemas at 2K, and most cinema projectors are 2K. Yes, most films are mastered and distributed at a resolution barely superior to 1080p.

In most respects, for the purposes of media consumption on a rectangular screen of any practical size, 4K already exceeds useful detail levels. 8K is absurd. Technology and content innovation should focus on high frame rate and high dynamic range.