I don’t really know that function development and health have a direct correlation.  I think you can develop or not develop functions and still be a perfectly… functioning human, as it were.  Maybe think of it more like learning skills, where doing so does not make you inherently more or less healthy.

I was just sent this 2016 podcast of Dario Nardi which may interest you. He does answer some questions in a similar vein and gets into some type specific things.