I think it is actually very likely that people would chose a programming language or system for reasons other than how competent they are with it. E.g. to seem "smart" because you wrote your compiler in Haskell, even though you actually have much more experience with Java or Python.
FTA:
> Another interesting thing to note is that at the start of every offering of the course the professor says that students can use any language that can run on the school servers, but issues a warning that teams using Haskell have the highest variance in mark of any language, with many teams using Haskell overestimating their ability and crashing and burning then getting a terrible mark, more than any other language, while some Haskell teams do quite well and get perfect like my friends.