I mean it is conceptually related. Half the point of HDR is that the filmmaker can say “I want this bit to be this bright (or dark)” and then it’s that bright when I play it back myself
So you're just repeating the assertion that SDR vs HDR and absolute vs relative brightness aren't orthogonal, but haven't even attempted to explain or construct an argument to justify the assertion.
I think it's quite obvious that you can have a system to represent 17 stops of dynamic range without anchoring brightness to an absolute scale, and that you can have a system to represent 6 stops of dynamic range that is anchored to an absolute brightness scale. The two properties are separable.
The only reason that you can get away with saying "half the point of HDR is that the filmmaker can say I want this bit to be this bright" is because of exactly the conflation I'm criticizing: the "HDR" label as used for marketing was redefined to mean high dynamic range plus a standard representation that encodes absolute brightness.
I think it's quite obvious that you can have a system to represent 17 stops of dynamic range without anchoring brightness to an absolute scale, and that you can have a system to represent 6 stops of dynamic range that is anchored to an absolute brightness scale. The two properties are separable.
The only reason that you can get away with saying "half the point of HDR is that the filmmaker can say I want this bit to be this bright" is because of exactly the conflation I'm criticizing: the "HDR" label as used for marketing was redefined to mean high dynamic range plus a standard representation that encodes absolute brightness.