Yeah, T was/is (usually) a pretty good listener and (usually) does what we ask without a lot of drama, so we've never been inclined to up the ante. He's a sensitive little guy that can't stand to think that anyone is "mad at him" (in fact, I think that will be a separate issue that we have to work on as he grows up, learning to stand up for himself and not "people-please" simply to avoid having people be mad at him.) Point being, every kid has their own challenges and personalities, and some of them respond better to different styles of parenting and discipline.
BCE - thinking about what you said about not being able to reason with toddlers, that still doesn't sound like an okay excuse. If I was caring for an elderly person with Alzheimer's that was too confused to be reasoned with, would it be acceptable for me to start hitting them to get them to do what I say? Probably not. That's what saying when I say that I don't understand the social mores behind spanking. If it was anyone other than kids, the onus would be on me to find a better way of getting my point across or find someone to help me if I couldn't, rather than resort to getting physical, right? But when it comes to kids, for some reason, it's okay. And I do get that society says it's okay, and that lots of kids get spanked and they are just fine and don't seem to be any worse for the wear and actually benefit from it as opposed to if the alternative was no discipline at all. Like I said, I was spanked, and I don't hold it against my parents and I'm as normal as anyone I suppose. But some corner of my psyche honestly cannot wrap itself around the exception of physically hitting kids. I'm not kidding when I say that I don't get it. My brain literally does not understand it. I'm not being cute, it literally does not compute. In the spirit of full disclosure, my therapist tells me I have a habit of thinking too much in absolutes. This is most likely an example of that.
Your therapist is presumably warning you against "black and white thinking" one of the many cognitive elephant traps that tend to interfere with our equinamity. Against that, the instinctive and unequivocal recoil from hitting your kids is part of your psychological make-up (as it is of mine) and you have to run with that. The danger lies in assuming that your instinctive repugnance for corporal punishment sets a universal moral standard. I'd add, that while I think there is no doubt that corporal punishment does not automatically have damaging consequences, I nevertheless think there are convincing and objective arguments for banning it.