Redditor and apparent appliance guru zjunk explains it this way:
Thanksgiving is almost here in the States. Having worked for a major appliance maker, I learned something interesting about ovens with a self cleaning feature. The self cleaning feature is the most abuse the oven goes through, with temperatures cranked up quite high to burn off the grime that accumulates inside. Because of that, it's the most frequent time for an electronic control panel or other sensitive part to fail.
What happens around the country every year on Easter, Thanksgiving, and Christmas is that millions of old folks have all of their kids and families coming home. Everybody's excited, there's going to be a big meal, etc. As part of the prep work, grandma self cleans the oven and then whole appliance dies because of a bad panel. Because a million other people in the country did the exact same thing, the parts aren't available and repair shops are all closed or over booked. Thanksgiving is ruined.
Dramatic? A little. (Thanksgiving is ruined!) But they make a great point.
While you're swiping every nook and cranny of the house with window cleaner and bleach wipes, leave the grime inside the oven alone until after the holidays, when repairmen are readily available and you're not relying on the oven to host 15 for dinner.