The why is probably like my local dealerships. Really, you don't stock plugs, thermostats, thermostat gaskets, and coolant for the 4.0?Yeah the ones close to me out here are the same way.
When I used to do Bimmers out east there was one dealership that was just a parts powerhouse. Whoever was running that parts dept turned it into a great operation - it almost rivaled Pelican Autoparts which is one of the online go-tos for Bimmer nerds. I've always wondered why more franchises don't make an attempt to grow like that.
They have had to order everything in from the LA warehouse for me and I've bought 1000's of dollars worth of parts there.