in reply to Certifications are dumb.
I think that you are slightly off in referring to people who are team players and loners. You should focus on is communication skills and how well they can share and exchange ideas. Good ideas can be like a virus, infecting others with concepts and energy but only if you have people that are willing to listen.
The worst people I have worked with are smarter than the average bear( this is not a generalization, but an observation). Their ego has gotten too big and they stop listening believing that they have nothing left to learn. They are also piss poor communicators because they cannot explain concepts to other people( must be their fault that they are not smart enough to understand... ).
The worst part are these are the sort technical people that end up in key positions in their organization. Most people who don't want to deal with the crap and have skills leave for another position. You then have no one else who knows the system and can support it. It turns around continues to feed their ego that they know more than other people and it is a nasty cycle. So when I see the lone programmer I think of this type of person.
Personally I like to program alone because I find it easier to concentrate on my work. But I don't consider myself a lone programmer because I like to interact with other people to learn what they are doing and exchange ideas. How can you become a better programmer by locking yourself in a room?