This is why I don't buy the " It's their first time as parents" excuse. A 30 year old does not need to have been a parent before to know that insulting a child is wrong. Beating a small human is wrong. Some things are just common sense as an adult.
Parents can say the most hurtful things to you while your brain is still developing, shape your entire adult mindset, and then forget they ever said it by the next day.