bizzelz...calling you a new car salesman wasn't meant to be anything derogatory, it is simply the way you sounded as you were pushing a lease over a buy, that's all. Sounds as though you may have some issues you may want to deal with.
As for the dealers having nothing to do with the cars after they are turned back in, well that's a bunch of crap. The dealer I worked for was called Walin Motors, (not there real name) the lease car company was called Hafflin Leasing (again not there real name) both companies were one in the same. To distinctly different corporations, but owned by the same people.
The dealers simply likes to insulate themselves for all different kinds of reasons, but the end result is still the same. Leasing pays the Dealer/rental agency a premium over what they usually make on a straight new car sale. That's why they promote it. That's why they taught you how to sell it. It's in there best interest, not the customer.
It isn't some sort of conspiracy, it's just what the dealers do to make money.