The power supply and LED current regulators must create a precise electrical environment to assure LED longevity. An LED does not typically fail like an incandescent bulb, suddenly leaving no light. An LED fails by slowly diminishing light output over time. Protecting the LED from damaging electrical events and controlling its operating conditions is the primary purpose of the power supply.
If one were to compare the life expectancy of a well-designed power supply to the life expectancy of an LED one would find that the power supply is between 100 and 500 times more likely to fail, for example, within a 10-year period. ALLED power supplies are designed to operate in difficult environments and last as long (or longer) than the LED.