Mix-tapes have been around forever, they just did not materialize very well in the web. I have created a similar software called Audius (audius.rockdapus.org) 3 years ago for the same reason. If you listen to a wide variety of music, algorithms only get you so far, in the end you need random inspiration from your friends and strangers. The last 3 years I have discovered tons of new music through algorithms AND my social music networks. I have build up a music group with my friends and joined several other music groups and I can assure you it's much more than marketing.
To the user engagement it's the same as in all other (social) networks you have a quote of 1 out of 10 people (if you are lucky) that post content and only a critical mass of engaged people will keep a community alive. An interesting read on this topic is also https://www.reddit.com/r/slatestarcodex/comments/9rvroo/most...
Hey there I created Audius about 3 years ago for the same reason these guys created their app: algorighmic music recommendations get boring after a while.
I extended Audius with the Matrix chat network to chat and share music, all with YouTube/Vimeo/mp3 Urls (so it's completely free and no registration is needed, all data is stored in the borwser)
Audius is also a progressive web app so you can use it like an app if you want to.
It's also open source, and has a single HTML file that you can host on any server.
To the user engagement it's the same as in all other (social) networks you have a quote of 1 out of 10 people (if you are lucky) that post content and only a critical mass of engaged people will keep a community alive. An interesting read on this topic is also https://www.reddit.com/r/slatestarcodex/comments/9rvroo/most...