Drawing from SDT (self-determination theory), one of the main predictors for motivation is a psychological need called 'competence' (perception of whether your actions lead to the feeling of growth or accomplishment). Different actions and situations can send either a positive competence signal to a person (and increase motivation) or a negative one (and decrease motivation). These things are measurable.

The main issue with competitions is that they send positive competence signal to one person (winner) and negative to everyone else. Like you trained for months, and now you've lost. This leads to increased dropout rates in sports, which are especially pronounced in kids. Norwegians asked the question – instead of spending money and effort to try to engage people and kids in sports, maybe we should ask a question, 'Why do they drop out in the first place' and prevent those? Competitions came as one of the strongest predictors of dropping out of sports, hence the policy.

If anything, the hardest part about sports is that you have to be the sort of person who can try their hardest, compete, lose and then use that as motivation to further improve yourself. Do you know how it feels to give something your all, and then fail - all in front of hundreds of people counting on you? And then come back from that? It's not easy. Behind any champion you're going to see a lot of pain and loss that they had to overcome. It's not like you're born a champ and everything is just easy. People of course are not equal, but the struggle is something we all deal with, and sports really helps with that.

On the other hand, I think that there are kids who are coordinated/sporty/physically talented and just as we celebrate and nurture the academic talents of academically talented kids, I think it's good to celebrate and nurture the talents of physically talented kids. Not everyone is going to excel at academics and if we steer schools to only encourage excellence in certain areas, I think we risk discouraging those who excel in other areas from feeling good about themselves.

Re: petere, it's not about Romans, rather the original meaning that provides insight into the pure form of competition. There is a great book called "True Competition" by David Shields that explores this topic and tries to answer the question "How to make competitions more healthy so they don't deteriorate into something that destroys the original spirit of competition".

It's also interesting that in English word "competition" is also used for business, economics, biology, and political sciences. In business, it's clear that competition is a tool to incentivize market players to pursue the highest quality of service at the lowest cost ("show your best"). Again, in monopoly/monopsony, there is no competition – we need other players for that – and no incentive to "show your best".