Local traffic in stock was some of the first business lost to an improving road system.
Not to mention the race to develop an economical and reliable refrigerated car.
I would imagine that the refrigerator car did more to hasten the demise of the stock car than anything else.
A little duscussion regarding tie-cars here:
I seem to recall some of the newer B&O stock cars that were converted to tie service and the roof had been cut off.