Why doesn't Questbridge allow arts supplements?

I’m a really talented musician and its one of the main things I was banking on to get me in to top schools like HYP. On the Questbridge website, schools like Stanford say that they don’t allow arts supplements for Questbridge. And other schools like Princeton and Columbia don’t say anything about it. Can I submit arts supplements to those schools?

The QB process does not lend itself to an organized review of artistic supplements. There are various ways to have your talent described by others and your passion by yourself. Think essays, LOR, and additional information. Nothing precludes you to add a link to a site that presents you in the best light possible.

After all, artists are supposed to be creative!