Or more charitably, the life of light bulbs was artificially shortened to avoid a race to the bottom with long-lasting but inefficient bulbs. Hot-running incandescent bulbs emit more of their radiation in the visible spectrum instead of infrared, but they burn out quicker. Colder-running light bulbs last longer, and that's obvious to consumers, but power bills aren't itemized so they're less likely to notice the wasted energy. The actions of the Phoebus cartel were arguable in the interests of consumers.