I agree that the number is probably not zero, but I believe the majority of drivers who made this error were rookies who learned from their mistake…at least I hope so.
Mike, how do you rear-end a car that isn’t in front of you?
Well, I can’t argue with the point that you’ll slow a bit more rapidly by letting the engine RPM drop and letting the pedal up, but that is a lot harder on the drivetrain. It’s not the technique I’d recommend.
If in traffic I’m a firm advocate of using the brakes. On the country roads in New England on a nice summer day just exploring with nobody around it would not be uncommon of me to downshift. Folks that prefer to always use the brakes are certainly driving safely and beyond reproach. It is actually the safer way.