I understand your skepticism; however, it absolutely will if you're a parent or someone close to someone with the condition. It's not in the DSM because the process for a diagnosis to be accepted usually takes years, and this is fairly new. Your points are acknowledged throughout the information on PDA. The best two websites I've found are:
https://www.pdasociety.org.uk and
https://www.autismwestmidlands.org.uk/wp-content/uploads/2017/11/PDA-1.pdf
If anyone needs a diagnostician , Dr. Donna Henderson at Stixrud and Associates is outstanding.