To add to the discussion, agreed; there used to be more selling points to a camera rather then just HD, 4K etc.
Mega Pixles used to be more of the focus, but what really matters are the quality of the photosites, the bit depth and how the codec can handle highlight roll off.
If you haven't already, Steve Yedlin ASC has an amazing video essay that really breaks down what is important when selecting a camera. The major take-away is that manufactures are locked into a pointless race to add pixels without considering the quality of the photosites.
NoFilmSchool has blocked me from linking to other sites, but just google, "Steve Yedlin Resolution Demo" and check out his video essay.