I don't have kids, but my gut tells me that raising a kid is one the hardest things you could do. Trying to take care of someone who doesn't always respond to reason or logic day after day seems exhausting. I understand it when parents screw up.
That being said, I do think there are things a parent could do that go way over the line. Things that cannot be excused by exhaustion or frustration. Things like, I don't know, everything on this list.
Parents shouldn't threaten violence or teach them to be jerkwads. Do you know why? Because that is how we get violent jerkwad adults who teach the same bad lessons to their kids, and on and on the cycle goes.
Also, all the other reasons why you shouldn't be saying these things.
Just had this happen today. "Hold the dog's leash, or I'll strangle you with it!" This was said by a father his five-year-old kid. The dog was a young-ish looking German Sheppard.
This actually was said to me.
I'm a dancer and used to compete on teams and as a soloist. (I don't compete anymore, college probs) One day, I was competing my solo and just touching up my make up in the dressing room where I accidentally was in the way of a mom and her daughter who was my age.
I said "Sorry, I'll be out of your way in a sec." and the mom says I'm totally fine and something about sharing a bathroom with siblings. I laugh and say "Oh yeah, I get you, I have three younger siblings myself." and the mom says "Really? I would've stopped after you!" Right in front of her kid. I smiled uncomfortably, grabbed my bag and moved to the other side of the room.
Let's all try to do better, shall we?