Actually, it does. Wal-Mart won't sell music that has a parental advisory sticker, so at the very least, an artist has to compromise their music in order to be put in the largest retail chain in the world.
Having your artistic creation 'scarlet lettered' like this is something we condemn when applied to other forms of media. Think of the outrage surrounding Facebook and Google implementing labels for news they deem fake or unreliable. Though such companies are within their rights to do such a thing, many consumers recognize the chilling effect this can have on distributing information and also adds a layer of needless obscurity to the process of reading the news.
The music industry does not employ a 'rating system' like the film, TV, and video game industries. Rather, it's a catch-all for any and all content that arbitrarily may be viewed as offensive to a broad demographic of potential customers. This takes the label from a mere rating system to more of a form of soft censorship.
I've seen albums that are largely instrumental labeled with the parental advisory sticker, because the sounds are intense and experimental. I've seen the sticker on albums whose only crime was being critical towards a religious institution. The label does a lot of harm, while I am not so sure how helpful it truly is for parents.
The caloric content of food isn't arbitrary, it's measured by a process that can be independently performed by anyone with the right equipment and get the same result. There's no similar process for deciding if artistic content is appropriate.