Musicians don’t use ‘one’ music creation mechanism. Musicians use instruments, sure, and musical scores, and they also use audio processing and production systems and digital audio workstations and MIDI controllers...
Some musicians use woodworking tools and materials science to manufacture new instruments to make new sounds. Others use CNC machines and 3D printers. Some use soldering irons and electronic components to build audio processing units and tone generators.
There’s a very active community of modular-synthesizer musicians who take electronic devices and patch them together, adjusting knobs and flicking switches to create music.
And there’s others who build all those same capabilities in software.
And Sonic pi sits on that tradition - of bringing more powerful programmatic tools to bear on the configurability of signal generators and sequencers and audio processing chains as a means to create music.