I think it's often used with younger kids because parents don't understand why their kids are acting up and can't work out how to "get through" to them. As kids get older they become a lot better at understanding and really words should be the only tool you need.

The dreaded phrase "I'm not angry just disappointed" should cut deep when (rarely) used because the kids understand their parents have their interests at heart. If they don't then something has gone wrong building that relationship of trust and respect.

ETA: forgot to say of course positive reinforcement is also key. Kids need to know when they get things right so they are not walking on eggshells worried about getting things wrong.

Agreed. But that doesn't effect my point, or even the study.

Almost everything with an effective appropriate use can also be misused.