That's never been established as the reason for the discounting, as far as I know. In fact, in one of the several threads about this set, here, some of our European Board Members discuss how their Universal-distributed Farlow sets also have these words on the spine, including sets that were sold at full price. In fact, common sense would seem to militate against that explanation, since it would have cost Universal substantially less to just replace the box tops with "Concert Band" on the spine, instead of taking a hit of more than 50% off the sale price.
We've yet to hear an explanation from Mosaic or Universal of why the Universal Farlow sets have been widely sold--and continue to be sold--at such a substantial discount off the Mosaic price. It would be interesting to hear such an explanation if anyone can ascertain it.