The Little Red Riding Hood Constraint
Little Red Riding Hood is a fairy tale in which a little girl is sent on her way to grandmother who lives on the other side of the forest. Her mother tells her to stay on the road, because of the dangers she'll encounter in the forest. And sure enough, The Big Bad Wolf lures her into wandering off the path to pick flowers, thus winning time to unfold his evil schemes.
It has never been made clear to me how staying on the road would have saved Little, but I'm probably missing the allegorical meaning of a young girl coming into adulthood.
In any case, the tale lends its theme to similar dangers in deploying software configurations that are 'off the path'. Staying with a supportable system saves time, effort and grieve. But as always, there is a delicate balance between something that is supported, and something that actually works.