I think it's a custom of the school at this point. It has probably been been there since the school was founded. I think it's fine it just needs rules that are explicit about the activities that will make you loose or win points instead of the biased judgment of teachers and events should be held to win a big number of points. Like if you get extra points for exposing certain subjects and replicating magic/potions in class we would have more Hermiones in the school