Any Honda salesmen in here? Why won't honda sell me a car?

I live in Southern california and I'm in the market looking to buy a new car. I've gone to a few dealerships ready to buy, they try to get me to finance with Honda and offer $750 rebate to sweeten the deal, I say no, I'll pay In full with my check from my credit union, I let them know I don't need the rebate and I'll buy the car at the price pre-rebate but they refuse to sell the car to me. Why won't Honda sell me a car unless I finance with them? Are there any Honda salesmen here that can shed some light on this?