There are still a lot of stores, but they are more and more carrying only the quick moving items. If you need a part for a grill that you purchased from HD that was their standard brand, you probably have to buy the part from them for in store pickup or shipped. They don't sell enough to keep them on the shelves. The problem with that logic is, if I know they won't have that item in the store, I'm not going to the store. When I go to HD, I typically spend a lot more than $5 for the seldom purchased grill part. Without that being in stock, they lose all of the other purchases too. From what I've been seeing, all the box stores (HD, Lowes, Walmart, etc) seem to be following the same logic.
I know a lot of people are very happy buying online (and I do it a lot too). I just feel that if I need some nails, it would be easier to look at them in person next to the project in the store to confirm that it's the right size/type rather than waiting 3-4 weeks after guessing at what is actually being sold.