[francis_t_catte]

it's likely not the dimmer's fault; phase angle triac dimmers were designed when resistive loads (incandescent light bulbs) were king. except for the super-low-wattage-per-lumen type, most LED light bulbs I run across these days are based capacitive dropper power supplies, which are inductive by nature (hence their atrocious power factor). combining that kind of load with phase-angle dimming is a recipe for crazy harmonics many orders of magnitude higher than the 60Hz base frequency.

[dfox]

I assume that design based on something like TPS92411 actually ends up being cheaper and more reliable than various series capacitor constructions, while being dimmable just fine and without spewing EMI. So it is just question of the OEMs having one 10 year old design and still using it.