Musicians and studios don't generally tend to offer the public access to original stems for songs (why would they?)

Say that you want to make a remix, mashup, or otherwise use sound-bytes from a song. The easiest thing to do is use a tool like Spleeter/Demucs to separate the source layers so that you can then further process them in your DAW.

This is what I do, but I just use the Demucs CLI because it's simple enough.

https://github.com/facebookresearch/demucs

Are there no communities of "open source" music? It sounds like the stems are part of the "source code" for tracks.

Many niches in electronic music have small knit communities of creators and producers that regularly remixes each-others stuff. But it is not an open community, you gotta have a decent standing (from making own music or prior remixes) before someone is willing to send you their stems. For anyone musician that has a label/publisher, they also need to be in the loop, for handling of the royalties. So sharing stems happen regularly in the music industry, but it is not easily accessible. Which makes tools like the one mentioned very useful for everyone else that would like to participate.

It isn't really in the best interest of the artist to provide this. The final mix is part of the overall product / work of art. Providing all of the individual tracks (there could be 30 or more in total) would also take up a lot of space / increase processing requirements while benefiting very few.

I usually use this kind of tools to get the bass score of some songs, for example. With the isolated elements it is much easier to know exactly what notes are sounding (I don't have a good ear). The same for drums or synth notes.

As after all the sound quality doesn't interest me too much to do this, I usually use iZotope RX, but I will try this tool.

This is like asking why we need decompilers.

> (In general)

Yes, I agree.