I am not a professional music producer, but I do produce music as a hobby. I'm also a sysadmin, so I know full well how to self-host everything myself. But it's just such a pain it's not worth it for me. So much easier to just upload it to Soundcloud and let them worry about serving it and maintaining it.

Now, if a sysadmin like myself won't bother, I really doubt your average musician with relatively weak or non-existant sysadmin skills is going to bother self-hosting. Professional musicians might hire someone to do it for them, but most music producers aren't professional.

That said, I stopped uploading my music to Soundcloud ever since they dropped groups. That was the main way I shared my music and discovered new music myself. Soundcloud is not mostly just a static music storage service for me now, and without an easy way to discover new music, it's not even worth the bother for me to upload anything there anymore.

I'm now hunting around for a good Soundcloud replacement.