It sort of does when it lists some of the areas made difficult by the lack, but you're right, it's definitely not a scholarly article. But when you think about it, it makes a lot of sense. The ONLY purpose of language is to communicate with our fellow humans. If you're not developing a good understanding of those humans at the same time as you're developing your language skills, problems are going to creep in. I often see it with kids who lack skills in describing and storytelling; if you ask them "What did you do today?" they say "I don't know," but if you say "Did you enjoy playing tennis?" they can manage to tell you a bit about it. It makes therapy tricky because you have to actually outright discuss metacognition with a four year old sometimes and that's hard to do. One of my favourite ways in is Lego or games like "Guess Who". The features some of these kids choose to ask questions about though! I remember one little guy asking "Is your person on the down-low?" That was a long discussion about what another person can and can't be expected to observe and what would be the most efficient way to win the game! Do you have journal access via a university or something? I can definitely hook you up.