My parents used to have the same view when I was a single child. Then my brother was born.
There are only so many times you can empathize with someone who keeps trying to do the same thing, despite knowing why he can't.
They still believe that explaining why something is forbidden is the best course, but they stopped assuming the person on the street slapping his/her kid's bottom is just ignorant of the advantages of compassionate parenting.
I'm not at all saying that the same tactics work for all kids. But there are tons of ways to influence kids' behavior that don't involve corporal punishment, and I've never had to go too far down the list, when I sit down and brainstorm ideas.
It's also essential to think longer-term. I don't know what your brother was doing, or what your parents tried. But part of raising kids is being aware that a child's behavior is going to keep changing, week to week, almost regardless of what you do. So if they're doing something you don't like (but that isn't risky), it's sometimes the best course to just endure it for a bit.
Personally, I'm pretty open about these things, so I remind my kids that yes, they have the power to make me miserable, any time they want. Sometimes they do. But they're clearly not enjoying those times either, so we work together to try to figure out what's going on, and how we can optimize for more fun.
There are only so many times you can empathize with someone who keeps trying to do the same thing, despite knowing why he can't.
They still believe that explaining why something is forbidden is the best course, but they stopped assuming the person on the street slapping his/her kid's bottom is just ignorant of the advantages of compassionate parenting.