meierlde
Thinks s/he gets paid by the post
It's kind of like no electromechanical device (or plain electrical or mechanical) is designed to function indefinitely due to general wear and tear (putting it mildly). Whether it's a car, fridge, vacuum cleaner, etc, all have parts that will wear out over use (time under use).
We as consumers don't have "inside" information as to what design life parts are spec'd to, but they certainly are designed to make it through a defined use life without failure (given some statistical specification). Also, cost of manufacture comes into play.
So, yeah, things wear out and replacements are part of the game.
Since appliances are the result of engineering the design lifetime comes into play. You can extend this at a higher manufacturing cost. I recall the 1930s 1940s fridges of 7 cu foot with just the compressor no fans no nothing else (my folks had one that was still going strong when the left it in the house they sold in 1986, bought in 1950, fridges back then were built on the kiss principal with the freezer cooling the fridge as it was a small chamber in the top of the unit with a tray for ice cube trays and perhaps 1 cu foot or so for frozen food. So units have come a long way in 70 years. (and in particular the cost in hours worked has come way down.)