I have one of those and I do.
Someone did that to me last night - I wasn't on the phone or texting and the light turned to green for no more than a millisecond before they honked. I politely thanked them with a wave and proceeded at 2 miles below the speed limit for the rest of the journey.The only time I use it (and too often unfortunately) is when the traffic lights change to green and the person in the car in front is looking at their mobile phone and not moving.