My experience is that martial artists with experience in fighting/sparring full contact can switch to sparring with light/touch contact in a realistic way. Distancing and body mechanics are correct, they can just hold back on the power. People who have only ever sparred light/no-contact have a tendency to get the range wrong. If you throw a fully extended punch at me and it comes up 1/4" short, that's not a demonstration of control, that's just you missing.
Curious. Why do you think people can dial power back, but not dial it up?