That’s a great point, though I wouldn’t underestimate the effect of a price on wine-searcher on the market (as opposed to a mystery wine price getting out by word of mouth). But you’re right, they wouldn’t do it if the deal was a sexy one to begin with…
Maybe I’ve been lucky but all the mystery wines I’ve bought have been either fair deals or quite good deals, though to be fair I only really bite on a small subset of them (WA red wine, OR pinot, under $40). It was pretty nice when I was just starting out to get some decent Washington red wines for less than half retail. I’ve picked up some Boudreaux cab and merlot for $20 a pop and a bottle of the Dunham Lewis Vineyard Merlot for $30. I’ve gotten some stuff I wasn’t trembling with excitement about for around $15 but they were certainly worth what I paid all things considered. I think if you’re far along your path and know what you like and are trying to build a cellar filled with specific things the mystery wine model makes a lot less sense but if you’re sort of new to wine, pretty much all wine is mystery wine even if you know what the label is so why not?