The problem (at least for me) is input format support.

Assorted foobar2000 plugins support every obscure tracker format, every obscure video game music format (.vgz, etc.), and then foo_midi lets you render MIDIs not just with Soundfonts but with whatever VSTi DLLs you like. Also support for music files in ZIP files as well as music files in ZIP files in ZIP files (don't ask). That's hard to compete with.

mocp opens MODs/S3M's and so on. Everything else it's handled by fluid/timidity.

VSTi's? Pipewire now can do that at system level.

>Zip

Here in Unix I can just mount archives and disk images.

> Here in Unix I can just mount archives and disk images.

This is so true! And it's much easier than just having the music player support zip files. Especially for zip-in-zip like GP described. Can you imagine double clicking an archive and have it play, rather than simply do:

    cd Downloads/
    ls
    mkdir tmp
    mount-zip myfile.zip tmp
    ls tmp
    mkdir tmp2
    mount-zip tmp/myinnerfile.zip tmp2
    audacious --new-instance tmp2 --play
    while killall -0 audacious; do
        sleep 1
    done
    umount tmp2
    umount tmp
    rmdir tmp2 tmp