In my experience the opposite is true.
Some people have an easy time programming, and the specifics - libraries, languages, etc - don't matter at all. They'll pick up that new stuff in their sleep.
I recently hired a Java guy after talking to him - he had all the right hallmarks so I was pretty sure he would be good. I gave him a task with a piece of software I am intimately familiar with. A good developer would have had to get up to gear for a week (40 hours), then code, test, work around the little kinks (there are many).
All in all an optimistic assumption of mine would be that this task would take a brand new guy a month. The dev I hired did it in less than a week!
These people are rare. They are the rockstar programmers. And if you find one, you want to hold on to them no matter what.
Team players? What if the guy can do twice as much in a week than a "team" of 5 mediocre guys?
To get back to your assertion, he then proceeded to learn Android and put a functioning app in the Google play store in less than a week.
Granted that's still Java, but the libraries are all different and developing for mobile is also different.
If I had an iOS job right now, this guy would get it, despite never having done iOS. He'd learn this in his spare time and then proceed to run circles around people who've been at it for years.
That's a rockstar programmer for you.