A post from the Steamworks developer group, as quoted in a Reddit post, explains:
The apparent demise of the flash and daily sales has already drawn mixed reactions from the Steam-using public, with some claiming that it will reduce the possible discounts while others point out that it takes some of the pressure off of consumers, but we likely won’t know how it plays out in practice until the sale’s over and the customer feedback is in. Whether negative feedback prompts a reinstatement of the flash and daily sales in time for the Winter/Holiday sale that begins December 22 remains to be seen.
