Maybe the product was created in a controlled environment (just like lab rats). Most people will not complain or pursue any other actions once they purchase a product, so the company is always ahead, even if they have to send out a new box to 25% of its customers. Eventually, there will be enough evidence out there to support that this product is really not the best way to reduce your CYA in any given condition. As always, people will overlook information and still continue to purchase the product.
If pool stores recommend a combination of tri-chlor, cal-hypo and liquid chlorine, with backwashing and possibly some water replacement during the year (which in turn would lower salt and TDS), most people would not run into this problem. Then again, most store employees do not even own a pool.