What tends to kill incandescents is the non-uniform thinning of the tungsten wire due to tungsten evaporating, which causes the thinner parts to heat up more, c

What tends to kill incandescents is the non-uniform thinning of the tungsten wire due to tungsten evaporating, which causes the thinner parts to heat up more, combined with tungsten's positive temperature coefficient, which causes a current rush on power-up when the filament is cold, which causes the weak spots to heat up particularly rapidly and potentially higher that they would if the surrounding wire was hot and thus had higher resistance (a cold tungsten filament has about 1/15th the resistance compared to when it's glowing hot). Transients certainly are one problem for LEDs if the power filtering is bad, another is (lack of) cooling - while LEDs produce much less heat, they also need to stay much, much cooler: A tungsten filament is fine at 2400 °C, an LED die should not get much hotter than 100 °C, preferably less than that, and most fixtures are not particularly good at getting rid of heat.