Ming from Agents of Speech explains why some children can sing or count but don't use words to talk: they see language as self-entertainment, not as a way to communicate with others. Teaching them to use words instead of gestures is simple in theory but grueling in practice because you can't just tell them to stop.
Why your child can sing, can recite ABC, can count from 1 to 10, maybe even to 100, but still won't talk to you, still won't communicate with words. Why your child does this is because of the language function. The function of this is all for their own entertainment. It's not to communicate with you. Therefore, they don't know that the same words can be used to communicate with you. Most of the time when children are pulling their hand or leading you or guiding you with their hand is because that's the easiest way, number one. Number two is that that's the only way they know. They don't know that words can be used to communicate. How do we solve? It's pretty easy and simple, but it's also excruciating process because you cannot describe in words, cannot say, hey, you don't need to pull my hand. It's impossible.
