"Controversy" involves many people who strongly disagree about something

It’s natural to want to help children with something as important as
language. Using baby talk with a child doesn’t help either. A lot of mothers speak to very young children in short simple sentences, with higher-than- normal pitch and child-like pronunciation. That certainly doesn’t do any harm and it may help get the child’s attention, but it’s unlikely to be crucial for language learning. Children in cultures where mothers don’t do this still acquire language without difficulty.