I would tend to belive that web-discounters may help ADB. Web-discounters may actually provide ADB with access to customers they may not normally reach through advetisment. Also, web-discounters may allow an individual to make a larger $ amount purchase than ordering directly from ADB. For example if a customer can only spend $15 on a product. the customer can now order more ADB products from the web-discounter than he/she could if they ordered direct, keeping the customer happy (which may increase sales in the long run) and increasing sales for ADB. In other words, the web-discounter would be paying ADB for two of Product A instead of one whereas the customer would only pay for one of Product A because of limited funds. Now I am not sure what the profit difference is for ADB between selling their products to the web-discounter or the direct customer, but I am pretty sure they are not giving their products to the web-discounter. Overall, by allowing a customer access to their products through a web-discounter, they may actually be increasing their profits.
Now when it comes to a brick and mortar store it is a different story. The sad thing is that brick and mortar stores are directly influenced by the web-discounters, which has led some of them to change what they present to their customers on the shelves (card games, 40k, clicks or what ever is the latest fad). It has also led the brick and mortar stores to become more competitive in variety of ways such as direct service and knowledge.
I usually order directly from ADB, that way I get exactly what I want and usually a little suprise (bookmark)

. Ocassionally I will trade and I sometimes order from my FLGS depending on how patient I can be. My favorite FLGS is a little different from most in that it is more of a meeting place than a store. It is owned by a group of friends that operate the store after their work hours and offer a gaming place first and a place to order products second. Not quite like a club, but kind of. They sell enough cards to keep operating, but I highly doubt that they are profitable. Great crowd.