I don't think there's any shortage at all and the truth has been touched on above.
I think this is exactly what's happening. Why bother selling to the public when a) they try and haggle on price, b) they ask 'ridiculous' noob questions, and c) they sometimes ask to return a watch, when you can easily seek to a grey dealer who a) buys in bulk, b) agrees a set price, which is possible above rrp and c) almost never has buyers remorse.
Of course the AD has to play their part in this sharade by towing the party line of "ooh a stainless sports Rolex? No they're in extremely short supply. Your talking a couple of years at least until I can get you one.
The result of this is that 1) people flood to the grey market, paying above retail which keeps the greys and in turn, the AD's happy, or 2) people buy a couple of models the greys don't want in attempt to get the AD to throw them a bone and buy the watch they wanted in the first place.