Pissed off at a crappy web company

What really is upsetting is when companies make defamatory comments about a business because of their own business practices. If you are running a web based business why would you offer items that you do not already have in stock? This seems like a great way to upset customers if you cannot get the items from the supplier in a timely manner. What seems best is what most successful web stores do, offer products that are in stock. Then you are not working with a credit based system or the "I promise that I will have something eventually that may or may not exist but I will take your money and use it in the mean time" system. But apparently it is much easier for a company to place blame on another if they fail to meet unexpected needs. I am surprised at times that any company would continue supplying another company when they do make defamatory statements.