He said that, basically, many of the stores that sell online get their merchandise from OTHER retail shops that are liquidating due to (mostly) going out of business. Some even approach legit retailers, agree to purchase large quantities with the obligation to sell them retail, but turn around and sell wholesale.
My only beef with online purchasing is, at many places, you don't receive the manufacturer's warranty. Even if you DO get a "store warranty", it's only good as long as the store is in business.
Having to send stuff back to the store via mail, UPS, etc., can be a pain in the butt and costly. And I like being able to look someone in the eye, tell him/her that he/she sold me a piece of $hit, and get them to do something THEN. Mail order, you can't do that.
Now this does NOT apply to those manufacturers that are mostly and/ or strictly mail order (i.e., IDI, Zeagle, Cressi, etc.).
Again, I'm just repeating what he said. Do I believe him? To some extent, yes. But to the majority of the extent, no.
Will I purchase most everything (if not all) mail order? Probably. It's just a tough decision when you weigh some of the other factors in. How do I size a wetsuit? How do I make sure the mask fits/seals properly when I have my regulator in my mouth? Can't do that mail order. And shipping back and forth until you get the right size/model/combination/whatever can be costly.