And the variations on "a little spanking", "spare the rod", "dad would take us out behind the woodshed"...

Careful studies have shown that violence used with children percolates back out of them, in rather rapid fashion. Something like a great majority of them go on to use violence to interact with others in the next two weeks.

So, yes, as it turns out: a little spanking did hurt... specifically, it hurt innocent bystander kids.