There's a full exclusivity effect to it. Make an item available for a limited time and poeple are more willing to buy it. To add to that you only need to stock enough produce for the time so you minimise waste. Win/win.
One of the other similar effects is the cost exclusivity effect. Make an item expensive and it doesn't matter how shit it is, people will want it for status value. Mercedes have run their marketing off this principal for decades. BMW had the same thing but they shot themselves in the foot when they introduced a cheap Beamer. Suddenly it's not exclusive to rich people anymore and BMW's stock plummeted.