“Photography is not rocket science. No need for dogmatic rules about which lens to use in what situation.”
If you are trying to reduce facial distortion then there is no question that it is infallibly true that there is less at a longer distances. and the effect is significant from 85 to 135mm equiv. That’s a dogma for sure.
If we are trying to ascribe rules of thumb of what appropriate focal lengths are for different situations (which, after all , is exactly why people call 85mm the classic portrait lens), then the rule of thumb is that 85mm is too short for a decently flattering headshots, not great for head and shoulder, but great for head and torso.
Started out doing photography at the age of 6 using an uncle's old 1940 kodak brownie box camera. At 15 years of age, I decided to buy my very own 1975 Praktica SLR camera. I now shoot with a Nikon D850. I do unpaid TFP and commercial paid work.