S&B's quality control is among the best, there's nothing lacking there.
The reason that most dealers don't carry them is profit margin, it's extremely tight. Many other companies have double (or more) the margin that S&B has. Everybody wants a discount to feel like they're getting a deal too.
They're also expensive and there's a lot of knob and reticle options so that's a lot of expensive inventory to keep money tied up in for this small profit. If dealers don't stock them then it's a two month or longer wait for a special order from Germany which most consumers don't want to wait for. So after you wrap up hundreds of thousands of dollars (millions in some dealers cases) for this inventory and it doesn't sell, then you liquidate it at a loss because there's not enough margin to liquidate and break even.
That's why dealers carry and push other brands. It's not for lack of quality or anything else.