This seems standard and entirely predictable progression of events, given that everything depended on proprietary, centrally controlled software and enormous pile of contracts?
You're not wrong. But if Spotify doesn't want to allow developers to be lab rats for wild and whacky ideas that are too risky for them to try themselves but could eventually either become or reveal the next big thing, they're leaving themselves wide open to major disruption.
I hope so! Not entirely is it true, network effects may be really powerful here. And "negotiate with 18383838 copyright holders" is not a small task.