Yes, why are deep learning models so effective relatively at writing code? It's because programmers have been making their work copyleft for decades, and continue to do so.

Musics only lagging because of the legal threat of labels, at some point in the near future music models will have their SDXL moment and from then on you'll be able to do all things like style transfer or make something very similar to this but different.

Suno and similar are purposefully limiting their models on the public side.