First off - let me say that I don't work in the industry, never have. I don't own or work for a dive shop. I consider myself a savvy consumer and I don't like paying any more than I have to for anything.
I may be niaive; but it seems to me that the two manufacturers in question have determined that in their own best interest it makes good sense to rely on a LDS to both recommend product to people who walk-in the store to get certified and have no idea what equipment is required and then to service the gear after the sale. So a person (the sales staff at the LDS) takes the time to educate the customer and explain what is needed and how it all works and then also to provide the proper training to use the equipment safely. Furthermore, most folks - experienced divers or not - don't have the skills or training to properly service the equipment regularly and keep it properly maintained.
So there is a real and legitimate need for a local dive shop with training and service available.
There are also a fair and growing number of divers who bristle at the thought of letting a dive shop make a fair profit, and grouse about paying anything close to retail prices. They know what they want, don't need a salesperson to tell them what to buy and like having choices in product offerings and paying deeply discounted prices.
So there will always be some company out there who wants to sell to them and will try to find a way to offer products for sale using the lowest overhead possible and try to discount it as much as possible to attract the buyer.
In my industry, there are NUMEROUS instances where the cost of warranty, insurance, sales, marketing, support, and contingencies (incuding defending against frivolous lawsuits) are all factored into the cost of good sold through distribution.
Many times those same products are sold outside the country for significantly lower prices and then somehow find their way back and are sold as "grey market" products. The process makes it very difficult for local US dealers to compete.
As much as there exists suspicion that back-door deals are being cut with on-line retailers directly from the manufacturer, and while some manufacturers DO cave-in and sell to the chop shops, it seems to me that SP and AL have too much to loose to be guilty of the practice. Doing so is like eating their young - it undermines the relationships they have with their core dealers and would eventually seriously erode their own sales - in the long term at least.
I am happy and proud to support my LDS. I don't always buy everything there - accessories and disposable items I shop for prices - but on my regs and BC I want to know I can get them serviced and I appreciate having someone I can call or visit for advice, and I don't mind paying a bit more for the privelege.
That's my 2 PSI.