The referenced analysis is including a ton of marketing & advertising expenses into variable costs which is probably not appropriate. If you're like Khol's where 75-90% of items are on sale at any given time, then it makes sense. But something like Plum District is more of an acquisition, marketing cost, not part of COGS.
My understanding is that was exactly the major misunderstanding. Plum District and similar were being used on most sales, so pretty much everything was always 50% off.
It wasn't just first time customers who were getting those deals, so it's not really an acquisition cost.
