I don't think you really mean that about Walmart!
You know, a lot depends on the LDS. One of my local dive shops is a Diver's Direct. Doesn't bother them where you buy your gear.
Another shop (the one closest to me) has a little store front down the road. Easy access to fills. He is the Henderson dealer I have mentioned before. His shop serves as the fitting room for people buying Henderson on line. He cannot compete with some of the big guys. His fault? Maybe for trying to get into the buisiness with less capital and buying power.
He is never rude about it, but he will tell customers if they buy their regs on line, they won't get the manufactures warranty. Is that bad to do? He is a USD-Aqualung-APEKS dealer. I don't think that is bad, I think it is marketing. "Buy from me. I can't quite match the price, but you will have a warranty."