Soundcloud started dying when they decided to be more like Spotify and less like the independent music discovery service they started out as. Now they have an app and experience that is not particularly good at either.
Specifically, members of some online transgender communities use it to solicit community feedback on their voices. They'll record themselves talking, post it to SoundCloud, and ask the community for input on what they could do better.
I don't think there's enough of a market for "pastebin for voice recordings" to be a successful business though.