Also there's the secondary problem that Spotify has an incentive to produce easy-to-digest content in house for which it pays lower (or no) royalties [0].
For you, the equivalent of problem #2 is your incentive to make deliberately addictive content of no artistic merit. Easy to say you won't do this, a lot harder when your backers demand growth and your analytics team demonstrates that Angry Birds For Tots will maximize engagement.
Don't get me wrong, I think you have a cool idea and I hope it works, but everything you say about your commitment to devs is cheap talk, and in my experience, such ideals tend to get discarded during, e.g., difficult funding rounds.
good luck!
[0] https://tedgioia.substack.com/p/the-fake-artists-problem-is-...