This isn't necessarily true. I tried to measure the PWM of my Cree and Philips smart bulbs, and what I found is that for RGB mode, they used PWM, but for white mode (which appears to use a 2700k led and 6500k led) they current dim both leds, and then use PWM to pulse the warm and cool leds on and off to achieve the target warmth. The Philips bulb actually syncs this so while the warm led is on, the cool led is off, and vice versa, so even though there is flicker, the total lumens eminating from the bulb is constant.