Thank you for this.

I'm just so frustrated, not only by the alleged "pros" getting their panties into twists, but by some of the fanfic defenders, too. In addition to everything you've said, fanfic isn't "just practice" or only a training ground for eventual original fic; it isn't any less an art form than original fic. It is a different type of writing — not inherently better, but neither inherently lesser.