Is this actually used anywhere? To me it feels like DAB and any putative DRM mechanisms have already been basically obsoleted by streaming systems like Spotify.

That's not the real rightsholder thing, as hardly anyone bothers with scrambled broadcasts; no, the real rightsholder handicap was limiting the bitrate of original DAB so it sounds worse than CDs.

It never mattered what the max bitrate was going to be, because as long as there was a lower bitrate option that allowed you to broadcast more channels, that was the option station owners were going to use. Because selling X ads makes less money than selling 2X ads.

Digital TV and radio were simply the first casualties of the modern advertising economy.