Interesting question. I’d assumed, after watching my two go through the application process, that someone at the college had keyed in a response incorrectly when setting up Common App. But maybe it’s as you say, the colleges want to keep some supps hidden. But… why? Annoyed students can just remove that college from their list; students who love the college already will not love the college more because of a new essay. Eh, seems like a terrible idea to intentionally have hidden essays.