One of the primary differences between an SMF and an audio backing track is... The SMF can be edited. You can mute out parts you don't want, you can mute out parts you want to play yourself, you can replace parts you think you can play better yourself, you can delete mistakes, you can seamlessly edit the song to a different structure, you can replace the drums (and the whole sequence) with an entire different groove.

An audio file? NOTHING. Nada. Zip. Oh yeah... whoop-te-do! You can change tempo and key (a bit, but not much).

I'm with chas on this aspect of it. Printing out an inkjet copy of a DaVinci masterpiece doesn't make you an artist in the slightest. It makes you a copy-boy.