...apart, that is, from Apple Music, Amazon Music, YouTube Music, Tidal, Bandcamp, SoundCloud... and even Facebook and other social media sites can be used by music distributors. There are even services that will automatically submit music to all of the major streamers. Also - and unlike Netflix etc. for video - they're not usually exclusive. If, as a consumer, I want to listen to a particular artist (even a modestly successful indie) I don't usually have to change streaming service. Even the "3 global listeners" trash in the bowels of Spotify is probably also on SoundCloud, the band's YouTube channel or somesuch.
I mean, there are plenty of other things wrong with the music industry, but anticompetitive gatekeeping by streaming companies isn't one of them. Not sure what you think the DMA should force Spotify to do that they aren't already doing?
With TV/Movies, if I want to stream a particular show I have to subscribe to the one streaming service that carries it.
Except they don't. and it isn't, so there's no tell other than your conspiracy theories...