I think Ethan is hinting at the fact that a great deal of successful musicians, songwriters and performers who make the grade on their own as a result of their own creative efforts and large fanbase...well, their work often bears little resemblance to the more orthodox songwriting sensibilities of a Jason Blume or even a Diane Warren. Many would utterly fail in "song school" but they have something very good nonetheless.

I also find that what Jason Blume does is financially successful, extremely difficult to achieve and worthy of great praise---he has a lot of talent...but his songs (sorry) bore me, and they DO appear derivative...

But he's certainly a success.

http://www.soundclick.com/MarkKaufman