Yes, nobody should view 5 year olds as valuable customers. Their parent or guardian can be, but you should not design a product that encourages the child to spend money, and you should not think of the child as the customer. The child can benefit from your product, but they aren't the one making purchasing decisions.
I feel it's worth noting that the intention is to remove any "purchasing decision". There is a "allow spending via Facebook" decision, and a key element is ensuring that customers don't question "but hey will my kid buy $10k cost of lootboxes when I'm not looking".
When people of any age click "get coins" or whatever, the system is designed to bypass purchasing decisions, reduce friction completely, make sure they're deep in to the "getting dopamine hits" like a zombie aspect of playing your game.
