HDR has problems that aren't the fault of missing color management. Notably, the fact that HDR of the HLG & PQ variety (so HDR10) do not have specified behavior. The specs are wrong in that they basically just don't exist for half the problem. Which also means most content is badly authored, too, almost certainly including your fancy pants Nikon. This is why gainmap images almost immediately dominated the mobile phone capture space, they are actually properly defined. So both viewers and creators know what they're actually intended to do.

The rest of your rant seems mostly anchored around the fact that most things still produce sRGB, which is true, but they still typically map inputs into sRGB appropriately (that is, they get clipped). Which still is being properly color managed.