Resolution is almost a joke these days.
For cameras: It all started with the megapixel wars. It's essentially pecker measuring for novice camera and tech nerds. You can easily create files with
XXXX x
YYYY pixels, but it doesn't mean that detail has actually been resolved at that level. I use professional DSLRs, and optics quality (glass) is a major limiting factor in detail. In consumer gear, it's both the glass and the sensors. I see people shooting "HD" videos that are no better than DV25 from a quality camera.
For playback: Even Blu-ray releases are often only slightly better than DVDs. It's more about the lack of care taken by studios or releasing companies, than it is the format itself. I reviewed a lot of Blu-ray discs and DVDs back in 2010, and often times the Blu-ray work was butchered, while the DVD version was not. How sad is that?
Given the lack of 4K sources (either homemade or commercial), I almost fail to see the point.
The pixels are there, but the resolution isn't.