The movie was more than a bit of a mess (though i loved it). To me the film had a few simple messages (in addition to the history of hollywood stuff that i'll pass over for this comment)

-how people get sucked in and intoxicated by Hollywood/movie making

-how Hollywood uses, abuses, and largely destroys the people that get sucked in

-movies are freaking awesome, so is all this grossness and evil worth it in the name of the art? (i think Chazelle leaves this one as a question, but think his answer is yes)

I really enjoyed the Toby stuff, but the movie would have been much tighter without it all