Might this might be a result of the type of people you spend time with?
If I think about college, I would also have said that the best programmers I know are the ones who I frequently see out doing other stuff. However, I didn't spend that much time with the more introverted people (not being able to relate to them as well) so its hard to say if they were better or worse.
I was more interested by the use of "frontline" in the original posting. It's not so much technical merit as your ability to, well, be a programmer (as a career).
> This seems to preclude being a social individual who happens to do CS some of the time.
The best programmers I know (and I tentatively include myself here; though Im really an engineer) are highly social work hard/play hard type people.