I am a firm believer children must reach a certain cognitive stage before they can be taught the intricacies of the English language. Grammar is confusing at best and baffling most of the time. But when the time is right, students should be taught the constructs of English, and they should practice them.
Early in my college career, I declared myself an education major with an emphasis on English. I excelled in every literature class, muddled through my writing classes, but was confounded when I took a course in semantics. What I realized is that I'd never been taught more than basic principles of the English language - plus the parts of speech. From kindergarten through twelfth grade, I'd never diagrammed a sentence! I had a lot of catching up to do (and probably still have much to learn).
I was surprised to discover the school district at which I was first employed did not require me to teach grammar. This was in the late 1980s, far from the trend of the 1970s, which was to abandon the "rules" and allow students to learn writing precepts by reading and listening. I was issued Daily Oral Language and directed to use it as the grammar component of my language arts classes. Amazingly, students were able to detect errors and correct faulty sentences without the benefit of terminology. They knew when a sentence didn't have a predicate, used the wrong verb tense, or needed a comma after an introductory clause.
At any rate, although I'm not a grammar geezer, I believe the basics are the basics for good reason. I'm pleased someone has taken notice!