It goes along the lines of you (me & DSis) were smacked and you turned out OK, so were your mother & I. It's a short sharp punishment, which is generally effective and then all's forgotten. We were smacked, not beaten and only rarely for really bad behaviour BTW.
Time out gives the massage that the behaviour (or child) is so awful that we (the adults) can't bear to have them near us.
It's mainly aimed at MY DSis, as her boys (2 & 3) do seem to send a lot of time on the step and he argues that any punishment you need to use a lot isn't working.
What do you think?