Someone might "rationally" come to the conclusion that the output of their work is extremely important, so much so that they are willing to sacrifice everything else.
The hardest I ever worked was at a small company with only six developers. It was surprisingly unpleasant, not because I had to code all the time, but because I had been a tech lead and had people to collaborate with on solving problems. This new place was all heads down devs, like some kind of throwback to an earlier age, and those people didn't want to chitchat--at all. Weird culture. I don't mind going off and coding and testing for hours on end and I was the most "in the zone" I have ever been on that job. Yet something was disturbingly missing and it was that openness to discussing solutions. I think it was the matter of resource constraints at small shops that annoys me the most, though.
How are you defining "effective" here? Anecdotally, all of the major bugs I've had to unfuck in the past years can be traced back to lack of due diligence. The "works on my machine" / "tested with N = 1" crowd.