"I agree with everything after your unsupported first sentence."
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.
The problem with your assertion is that it is inappropriate as a response to a concise description of what linguistics is. Linguistics is not the study of how to be a more effective writer or a great communicator. Linguistics is the study of the "basic" language communication skills that nearly everyone possesses. When you study linguistics, you discover that even what many people would consider to be poor speech or writing is still remarkably sophisticated and complex.
> The brain is certainly wired for language, but not for a specific language.
Can you explain how the brain is "wired for language?" Naively, I would imagine language is just one instance of the general pattern "things Hierarchical Temporal Memory models (e.g. the neocortex) get for free given a large-enough training corpus." Is that what you meant, or is there actually some part of our brains that is specifically "language" and couldn't be repurposed for something else?
It's not that the parts responsible for language couldn't be repurposed for something else (although I don't know whether it's true). It's the fact, that more general learning skills cannot substitute dedicated language learning capabilities.
It's hard to come up with different hypothesis once you know that children not exposed to language at all for some time (up to 4-6 years, but I don't remember) lose the ability to acquire it forever.
I think we have differing interpretations of "required"