Regarding Garth Brooks specifically, the lack of availability of his music on streaming services is entirely his own decision. He owns a streaming service called Ghosttunes that exist /solely/ for hosting and streaming his own music and refuses to make his catalog available on anything else.

Edit: actually looks like he sold it to Amazon a few years ago and it was absorbed into Amazon Music where his catalog is now available. Regardless, Garth owns the rights to all of his music except for his 2014 album "Man Against Machine", so the lack of availability is again entirely his own decision.

I'm just arguing against the "and you can listen to whatever you want, wherever and whenever." statement. It's just literally not true. Tool wasn't available until a couple years ago either. Sometimes I stumble upon major artists and am like, "Oh, wow. Why haven't I heard them in so long?" And then I see that they just signed a contract to stream.

It's annoying. I can't keep track of all the artists I like and listen to. There's hundreds/thousands.

Music not being available due to licensing stuff isn't really a Spotify issue, sometimes (like the Garth example above) rightsholders won't play ball no matter what. And the original comment was clearly generalizing, no one is expecting literally every piece of music ever to be available on Spotify.

So if we're going to be pedantic, you can add local files to Spotify on the desktop app and they will sync to your phone, so technically you still can listen whatever you want on Spotify.