Pretty sure it's from that one...I always reference Heinlein's quote about what humans should be capable of: It's a really long list that ends in "...specialization is for insects."

I always loved that, myself being an ADHD guy who knows how to do all sorts of things somewhat and still learning...

...but growing up in a world of people told to pick a single direction to almost-never stray from and avoid thinking outside of those lines.