As a flicker-sensitive person: the sad part of it is that to do this properly you need to have your LEDs on a proper inverter, so for most scenarios getting rid of the flicker means "get expensive light fixtures _and_ rewire their supply _and_ you can't use your existing AC mains anymore, nor can you use switches". The PWM is a cheap way to do dimming given the AC input of the grid. And it will be especially prevalent when you do want LEDs but you don't want to "do anything special" to make them work well
And effectively useless for dimming in the upper half of the intensity range.
You could of course turn on/off leds in an exponential fashion, but that would result in an impractically large light to be able to dim properly, and with increased cost (much cheaper to assemble fewer more powerful leds than many smaller ones).
