Capacitor Plague
This is a general problem with electrolytic capacitors, so is not restricted to Apple and any electronics with that type of capacitor will tend to suffer. It's partly dependant on how much headroom both the designer of the circuit and the manufacturer of the capacitor give between the conditions under which it is used and the absolute limits. the closer you get the limits the shorter the Mean Time Between Failures.
What's most fun is when the capacitors finally declare that they have enough and explode, emitting a shower of confetti when they do, along with the obligatory magic smoke.