What about my first sentence bugs you? The brain is certainly wired for language, but not for a specific language. English, for example, is not instinctive. A newborn baby will not spontaneously develop English; he will need to pick it up by being around others who are speaking it. Same goes for French, or Mandarin, or Russian, etc. I'm not going to spend all morning looking up and linking research papers on this topic, so I'll just need you to take a flyer on this. Either you're going to agree with me or disagree with me, and that's cool either way.
"I think we have differing interpretations of "required"
Perhaps, though it's probably not a semantic rabbit hole worth a deep dive. But sure, learning the rules of a language isn't technically "required" in order to attain basic fluency with the language. But conscious study of the rules is certainly required to break through plateaus in one's facility. I guess this ultimately boils down to what one's desired goals and outcome with a language are.
Either way, the statement "no conscious understanding of the rules is required" is overly reductive and sweeping.