Look at programming competitions from an assessment perspective: what are they measuring and is what's being measured good or bad for a job?
Ability to work under short time constraints (probably good), to hack out some solution that will work temporarily (good) but probably not solid (bad), to forego much time to consider the implications of design and implementation choices (bad), to develop without communication if solo competition (bad) or without communication outside of the small group of core developers (bad), to build a solution without getting feedback and refinements from stakeholders (bad), and so on.
Ability to work under short time constraints (probably good), to hack out some solution that will work temporarily (good) but probably not solid (bad), to forego much time to consider the implications of design and implementation choices (bad), to develop without communication if solo competition (bad) or without communication outside of the small group of core developers (bad), to build a solution without getting feedback and refinements from stakeholders (bad), and so on.