They once told me that it's important for them because of the deals most company have with big retailers that say they can even the price of any competitor.
For example, if Best Buy sells a keyboard X at 100$ and massdrop offer it at 70$, then Best Buy has to sell it at 70$ is someone finds this deal, but if you long on massdrop with an account and accept the fact that it's a group buy and that you can't use this price to compare elsewhere, then it's all good for everyone. If they don't do that, the suppliers won't make deals with massdrop.