You are mistaken. It was objectively the worst sale ever yet. Not saying I didn't buy a bunch of stuff, because I did, but they weren't even trying this year. There was no game, no gimmick, no competition, no flash sales, and no fun. Just a bunch of stuff with some lower prices for a long time. To me, Steam sales are events, and this year (judged as an event), it really sucked. Also, the discounts were not on par with prior sales, thus forcing me to fakey some stuff I otherwise would not have.
I'm pretty sure to make that sort of claim you'd actually need numbers and a well defined and agreed upon metric for what "success" is.
(Be that sales, total of unique user interactions, etc).
Subjectively, I found this sale underwhelming. The comic wasn't near interesting nor clever enough to bring me back daily, the Alternate Reality Game is not my thing and thus just felt wasted. Thanks to returns, there are no flash sales, daily sales or anything that drives me to visit the store at any point other than the very beginning or very end of the sale. Plus, it just was endlessly THERE. When there are no shifting of prices, there's no real reason for the sale to go on as long as it did.
Allowing refunds is a very consumer friendly action and I'm very happy they did it. I just hope they get their act together and realize they need to do something to reinvigorate their sales.
I'm surprised they didn't have a Gem auction all year... it seems just like the sort of thing that makes for an interesting annual tool to clear out the market of all those cards that have gone there to rot and die.
They also need to reexamine the smash value of cards. When the math is obvious that you should always try to sell cards, they're all just going to the market to rot and die... because there is no reward at the end of the tunnel that is worth buying up 3 cent cards to turn into badges. Either make more compelling rewards than "You gain 3 more friend slots", or make some way to make gems MEAN something. (More gem auctions, used as a currency for SOMETHING)
As a whole, gems are just woefully underused. They're a great tool to create rarity in their cards, make the cards have a non-trivial value, and if those cards sell in the market, the game maker gets a cut. The all should be more motivated to do things to get that market more thriving.
It's probably a difficult thing to balance, but I'm surprised they put it out there, did the one auction and have basically left the entire thing to die.