For a long time this has been a general rule. Just take the mean and substract two standard deviations and you get some useful reference values. Or whatever algorithm you like. This changed considerably where commercial or any other personal interests come into play. The cholesterin discussion settled only by studies showing that people with a history of cardiovascular disease may derive benefit from statins irrespective of their cholesterol levels.
I see some analogy in the vitamin D field. There is a German dermatologist who believes that 60% of all Germans are vitamin D deficient (the comments following the interview highlight this as an epiphany “totale Erleuchtung”). And a more recent paper showed that “89.9%” of all healthy newborns being insufficient. Really looks like a mix-up of some basic concepts in clinical medicine, yea, yea.