examples of successful musicians posting their work to social media sites when they were starting out
...and receiving little or no response.
Avicii (in swedish): http://forum.studio.se/index.php/topic/37778-naagra-laatar/page__p__602405
Alt-J (before they were called Alt-J: http://www.reddit.com/r/listentothis/comments/e6cig/breezeblocks_films/
WARNING: Don't scroll down the page on the Lorde link if you don't want to read homophobic/racist insults