Overthinking my earlier overthinking (I honestly can't turn it off once it gets started):

I remembered that the friend character shows up only once again in the movie, in the final montage meant to establish that it's been 2 years and Ariel's totally famous now. We see him pick up a magazine with her face all over the cover, and then it cuts to him giving a wry smile that might be "Good for her!" or "I guess she got what she wanted" with a bit of "See, I was right all along."

That's enough to make me think that the intention was much simpler: the point of their conversation at the beginning of the movie wasn't to cast any doubts on Ariel's motivations and/or talent, but just foreshadowing. It's him saying that she's not interesting because nothing bad has happened to her, and sure enough, she just needed to have something bad happen to make people listen. But they're still not listening to her so much as listening to the people who orchestrated a plan to make her their voice.

So I guess maybe the takeaway is "even if you acknowledge that you're riding the coattails of famous people to become famous yourself, you're still not using them so much as they're using you."