AUdiolab,
Might the dealers viewpoint be skewed by the fact that these traditional "audio" only devices is their bread and butter whereas one can build a very good computer audio system with a little know-how without ever having to visit those traditional shops?
Most larger local B&M shops in my area that are still around have major inventory and floorspace dedicated to computer audio related gizmos. As always, they sell the gear that is of better quality and easier to integrate perhaps than what one might put together themselves otherwise.
Myself, I make a living from understanding and applying computer technology, so I have not bought anything for that from an audio store to-date becasue frankly I will pay a premium there for nothing better than what I might assemble myself otherwise, but, as has always been the case, there is value in going to someone with that special expertise needed to deliver good sound still for many, though there are many other options out there these days than ever before. Overall, its a win win for everyone.