While I think your idea has some merit for sure, I think the difference is in demand for product. I think BD could pull off a model like that if they sold a hell of a lot more bikes.
It would take a great deal of infrastructure and overhead that they do not have now.
How they do it (as I understand it, and Mike please correct me) they essentially come up with a bike they want to sell. Lets say road bikes or MTBs. They design/copy/make a frame. Some are clearly models that were OEM at one point. That is made in Taiwan.
He gets parts. He buys those in bulk - they are also either made in Taiwan or somewhere close. He buys that stuff in bulk. He starts to setup levels of parts . . . essentially he groups stuff together.
So now he wants to do road bike. He has his upper level package of stuff (Ritchey WCS gear across the board). He puts that with a frame and then adds a level of Shimano. He sells the DA bike at $1500, Ultegra at 1200 and 105 at 1000. He has 3 different bikes with very little work.
Then he has some frames. A carbon frame is just like above, but at $200 more per level.
Same with MTB. The fly team, fly ti, and the high end FS bike all are essentially built the same.
The Fly 9357 is equipped like a FS bike as well.
You ca start to see the patterns he has. These are setup and assembled all overseas. 5 months later they are in TX or FL and ready to ship. BD does not open these (I am sure they do some for QA, etc). I am nearly sure when I let air out of a tire from BD that it is actually Taiwan air.
Mike is usually very open about his model, and is happy to discuss it.
His model right now is done with very little in infrastructure from an internal point of view. In the states he has a warehouse or two that requires very little in staffing - just take a box put a label on it and go. His technology costs are almost nil. His webpage (subject of many jokes) is not costing him a ton. His money is in ads.
Now, in case you get the wrong idea - I think this is a F***ing GREAT MODEL FOR BIKES. There is a segment that I am part of that is different. Many first time buyers. We buy like we would buy a thousand other things in our lives - research it and make the best choice on a balance of price and quality. We want a great deal and we are okay with not having exactly what we want. We want it fast and easy. Fitting is not hard and many do not need to be helped.
I love that I got a 17lbs full DA bike for $1500. A 21lbs MTB nicely spec'd for $1300 or whatever it was. I know this model is not for everyone. I personally would not be any happier if I had options on these bikes but ended up paying 20% more. Not saying that would be how much more it would be.