So does "friendly competition" mean "keeping score" but not offering outside rewards to the winner? I think "keeping score" is required for anything labelled as "competition" (friendly or otherwise).  Games or competitions that don't keep score are not much fun.  However, I think anytime a real "reward" is tied to the outcome of the competition it takes it out of the realm of "friendly", and weaponizes the competition. 

I think so, but it more comes from the individuals pushing themselves and each other to be better, rather than something mandated from outside.

So is it even possible to have healthy competition on a team?  If so, how?

Moreover, software development is commonly called a “team sport.” Assessing individual contributions in isolation can breed unhealthy competition, undermine teamwork, and incentivize behavior that, while technically hitting the mark, can be detrimental to good coding and good software. The pressure of performance evaluations can deter developers from innovative pursuits, pushing them towards safer paths.

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