I am also somewhat amazed as to why you equate the phenomena of burning-in to something that is deliberately engineered?
I assure you that engineers do have to worry about these kinds of things when designing equipment and not just the performance of the device on the day it leaves the factory.
Often the part selection and design criteria are heavily influenced by the desired products useful life span. Nobody wants a "lemon" out there that hundreds of customers complain about; the cost to make a manufacturing recall to get equipment to perform properly as originally specified to customers; the cost to reputation.