By that logic, the library of Babel owns the copyright on every piece of literature that could be written, which would be a terrible idea.
I guess for matters of copyright you have to produce a specific artifact, just blindly enumerating all possible artifacts is not good enough. Which would also mean that the existence of all those MIDI files will not make a difference.
If I were to write a "random book generator" that just regurgitate infinite text then I can copyright a pair starting index and length, but not simply all possible finite sequences of letters.