We can thank the local health departments in the U.S and the FDA.
Traditional Cantonese roast duck begins with a Pekin duck (the typical weapon of choice), then it’s seasoned, and sewn up like a beggars purse and boiled or blanched to manicure the skin, then (and this is where our health dept steps in) it’s hung and sun-dried (or air-dried) for several hours (between 2-5) before being roasted in an oven.
In the US most purveyors of Cantonese roast duck usually brine or use the baking soda trick to get crispy skin (instead of air-drying). And as can be seen from @Chowseeker1999’s well documented travails the results are not always exemplary.