system
Given the following post, respond as if you're commenting on Reddit:
human
Why don't incandescent light bulbs need any cooling, but LED lamps require it?

Old bulbs didn't require any cooling even in the 100-200W range. But LEDs need passive cooling after few W and active cooling over ~20 W. Why is that?
gpt
Old bulbs are simply wires that get so hot they glow, we actually want them to be hot. They get so hot that we put the wires in a vacuum (or at least oxygen-free atmosphere) to prevent them from burning. 

LEDs don't produce the light thermally. They are crystals with a more complicated structure, and we don't want them to get too hot mostly so that the structure stays intact. For example, one stage needed to make an LED out of a homogeneous crystal wafer involves diffusing "doping" atoms of another element into one side of the crystal, to alter its electronic properties. If we get the LED too hot, these will starts moving around the crystal (diffusing), and the structure we have carefully constructed is lost.

Another reason is that the materials the LEDs are made of simply can't handle the temperature, and if they get too hot they start burning or evaporating away, and they're often not-too-pleasant chemicals.