Why is this stealing? You can already listen to everything that's on Spotify with a free account. You are free to also record the audio while it's playing. I suppose grabbing the actual file should't matter? Or is this about releasing? And robbing people of plays they would otherwise get through Spotify?
Downloading it all in bulk is different than personal usage. Its like ai companies hoovering up everything.
If you listen to something on Spotify with a free account the artists still get paid. This isn't a case where you're ripping off so mega-corp. You're ripping off thousands of artists from major label ones to tiny indies. Take the metadata and build something cool. Stealing the files and releasing them is something else entirely.
> Why is this stealing?
It's not, theft involves taking something from someone, i.e. also depriving them of that thing.
This may be unauthorised copying aka piracy, but it's not theft.