Not entirely true. I've been to German driving school and my father really pushed the concept of smooth throttle control on me as a beginning driver. Be smooth always. However, as I was able to afford higher and higher performance vehicles my take on the smooth maintaining of speed without noticeable accelerator input has changed. While I'll drive my SUV very smoothly, when I drive my manual six speed German roadster, my style is entirely different. Because of the weight, size, and HP, it's really not possible to drive it smoothly outside of tossing it into 6th which isn't terribly "fun". In the gears where it's "fun", it's a very much "on" or "off" throttle experience simply because of the HP produced by the engine.
a) you don't want to drive them smoothing because that's no fun - even for just the exhaust note & b) It's actually difficult to drive them smoothly because of the torque/HP.
It doesn't mean you are a bad driver, it simply means you've adjusted your driving style to match the car you are driving.
I did a 6 hours trip with a friend continuously putting his foot up and down on the throttle, and it was the most gruelling car trip I've had I think.
When I asked he said it was "to keep control on the car". I'm a patient friend.