> But yeah they won't produce birdsong. There's no utility to that. I guess it's a matter of environment.

This is the crux of the issue. GPT-3 would happily learn birdsong instead of human language, just like it has learned to produce snippets of code or a sequence of chess moves or various other things found in its training data. For that reason, it's not by itself useful as a model of human cognition. Which is not to say it isn't interesting, or that studying LLMs won't lead to interesting insights into the human mind--I suspect it will!