Stonecutters Dealing Damage

I've seen the stonecutters have been updated to look likes powered saws. Although, I was thinking about how they don't hurt you when you touch the blade. Could that be an option? I don't know if I'm on a real suggestions page or if it's just a fanmade scam, but I really don't like the idea of defeating a Wither, falling down to bedrock, almost drowning in lava, only to come back up and find I can't be chopped to death. They would also make good traps, if you had a zombie and instead of walking around them like they do with holes, they limp straight into them. Could be an easier way of getting mob heads too.