This is already addressed in the article, e.g. here: There might, however, be a dark side to the story. There is a good reason we were designed to have

This is already addressed in the article, e.g. here: There might, however, be a dark side to the story. There is a good reason we were designed to have finite sensitive periods. Takao Hensch, a Harvard neuroscientist, has written that plasticity takes a lot of energy: It’s exhausting to keep all your neural circuits in a dynamic state. Restricting it may protect the brain. and in the paragraphs thereafter (I don't want to quote them here in full).