Nope, it's still there! Hidden in the Music app, since they really want you to just subscribe. There's also a separate iTunes Store app on iOS. Not sure what the situation is on Windows or Android, but it should still be available.

I personally use Deezer for streaming. For digital purchases, the iTunes Store and Bandcamp are the biggest platforms. If it's not on Bandcamp, it'll probably be on iTunes. Then there are CDs and vinyl of course.