I think this is more because of how people choose to spend their time. I know several outstanding programmers that are also great at learning foreign languages and writing poetry, and in fact, it seems that learning human languages and computer languages have some strong correlations in research about linguistics learning.

But, no matter how good you may be at any one of these things, to become good at the others you must spend time focused on learning and doing them. Most of the great programmers I know prefer to spend their time in pursuing other things that they become good at instead, primarily stuff to do with physical engineering. (Aside, I've always thought the propensity for using physical engineering as a non-work hobby is guided by frustrations from the intangible nature of programming/software.) But, I do in fact know several that travel and learn foreign languages, or that write poetry and short stories as a form of outlet.

They wouldn't be outstanding - they don't have specialized training.

But how do your outstanding programmers compare at writing poetry... when compared to your not-outstanding programmers who also have no specialized training?

If they applied themselves to those things the way they did to programming, there's a good chance they'll be outstanding or at least remarkably good in those as well.

Intelligence is a necessary but not sufficient condition for competence at intellectual tasks.