I don't see why they would put it on its packaging tho, i mean do HID bulbs say that they loose lumen output with time? i have yet to see that. When u buy tires for your car do they explicitly state that with time the tread will wear away? If im not mistaken, most CFL packages do state "initial lumen output" which should indicate to a consumer that they do in fact loose lumen output with time. Almost everything looses its efficiency with time, at least in an electronic sense. With time resistance builds up within the unit, much like a battery, u get more heat and less usable power, which then leads to the ultimate demise of the unit itself.