One can find lots of schematics for triac-based front-phase cutting dimmers. But there is neither schematics, nor actual products which would do proper PWM, where the circuit is switched on and off many times per mains cycle and amount of light is controlled by the width of the pulse (hence, PWM).
In my opinion, front-phase (triac) dimmers introduce too much noise into mains and cause filaments to make noticeable acoustic noise. I understand that PWM will be free of those problems, am I right? So, what is the reason nobody uses PWM for dimming mains lamps? Is it costs or power dissipation or EMI/RF noise or something else?
Thank you for your opinion!