Yeah, I’ve seen a few people say that but then there doesn’t seem to be any reasoning behind it… And some really cool essay ideas don’t really fit into any of the standard prompts. I think if they didn’t want you doing it they wouldn’t make it an option.
I guess to counter that one could say that the common app makes it an option but the colleges are the ones that don’t want it. Which is a valid point. But I think if a majority of colleges using the common app didn’t want it they would say something and the common app would change.