I accept what you say, and I personally have a good grasp on filmic. I can however see why lots of folks are confounded, and in my view some of this can be attributed the evolution of filmic in its various guises and the fact there is lots of outdated advice out there.
Aurelliene has in the past mentioned including a grey card and sampling from it. Bruce Wiliiams posted a video describing a Caucasian human face as being middle grey (which well-tanned Australian skin could well be).
This makes me wonder whether references to mid-tones and middle grey should be replaced with “the important bits that are to be preserved” or somesuch .