Legacy nodes (known in the industry as “mature” nodes) remain in use after they’re no longer cutting edge. Each run teaches lessons learned for improving yield or performance, so there’s still room for improvement after mass production starts happening.
Yeah, Spotify is trying to force the same thing with a similarly muddled interface.
YouTube Music is still worse, though, in that it’s also tied to YouTube the video hosting service, plus a music streaming service, plus a podcast streaming service.