Yeah this is what I don't understand as well, most of the polymath type people I know are naturally curious and self motivated for whatever it is they want to study and do. I am not sure what or how an institution can cultivate such behavior. I suppose it can encourage it to people but again, most polymaths are naturally self motivated and don't need encouragement at all.
They don't have to actively cultivate it but they should remove the walls between it. There's a lot of red tape/administrative confusion at most schools if you want to do anything interdisciplinary, especially if you want to cross more than two disciplines. Institutions should be more like buffets for the polymath. If I want to interlink say landscape architecture, sculpture, acoustics, materials science and biology I shouldn't need more than one signoff much less the 5 it would probably take to do work in something like that at most universities.
The way to 'beat' the system's hard testing requirements is to make the interdisciplinary programs more involved, more quantitative, and just be more thorough and engaging, including soft skills elements.
I think the best outcome is to have such students crush their standardized tests by outperforming them due to having a higher baseline because of the interdisciplinary program's curriculum.
There's a difference between "Create polymaths from scratch" or "Create a polymath degree" (oxymoron, honestly) and just "Let's have a learning environment that allows it".
They cannot force somebody to a polymath, but they can create an environment that promotes polymath-ing and allows polymaths to thrive, vs an environment that promotes overspecialisation. This can be reflected to a degree/study program to the extent that overspecialisation can also be reflected in one.
Even just putting together people from different background and trajectories can do miracles sometimes.
