I've also never hit an asshole, either. But I do fully expect to get hit if I'm harassing or treating someone in a manner that isn't appropriate. Anyone with siblings more or less figures this out through trial and error throughout their childhood.
In terms of hitting, my parents never allowed it, and I will never allow it, but kids are kids. They will get into a pushing/shoving/hitting/kicking/biting/scratching match with someone, whether it's a parent/sibling/playmate/etc. All kids handle discipline differently and I don't think it's necessarily wrong to spank if it's within reason if all other options have been exhausted. I've had friends who were flat out abused and what it can do is absolutely horrifying so I do understand why people are so sensitive about this. I was lucky enough to have, in my eyes, great parents.
To put my viewpoint in perspective, I was only spanked twice growing up. Once for stealing my brother's toys and harassing him, the other for pinching/hitting my dad. Timeout and getting toys taken away and sitting and having talks about it didn't remedy the situation the first few times. So dad decided to swat the butt a couple times. For me, it solved it right away. I'm not saying this is the remedy for everyone, and I hope I never have to spank my child, but for whatever reason, these two times really taught me a lesson in how to respect others and how to learn to handle my feelings in a different way.