"I think many of us are used to dealing with the likes of Henry Shires, Ron Bell, Ron Moak, etc., and an issue like this never would have occurred."
In all fairness, they would not process anywhere near the volume of product.
In any event, I have had a lot of good experience with MJ especially with price matching. Their CS has always gone that extra mile for me. Having said that, I haven't purchased from them in the past couple of years as they don't offer anything that I would want given my current UL focus.
The same thing happened last year with Backcountry.com 40% off coupon that was to be used only for the Outlet but worked for a short time on regular priced items. Some folks got lucky, others didn't. Again it happened with MJ last year on Western Mountaineering sleeping bags that were posted on deep discount.
This may have been a 'system' mistake or it may have been done by Backcountry and MJ to boost some sales volume. For those of you who received some great discounts - good for you. For the others, quit your griping.