I got a few good switch licks in my day. I feel it was effective but I wouldn't do it to my kid as I believe there are more effective deterrents. I can easily see how it gets passed down though. Spanking can be systemic in communities where ignorance to more effective alternatives is present.
If he spanked his kid with a switch a couple times I'm not going to condone it, but If there wasn't some sort of overreaction or excessive discipline I'm not so sure about an indictment.
My perspective may be different and/or out of touch as I was disciplined this way a few times, and within the community I lived it physical discipline (spankings) was extremely common.
My parents kept me out of trouble and focused on doing the right things, so I'm not going to question their methods In hindsight.