I personally think its more powerful than writing a new process to replace and existing.
My favorite example is an X11 windows manager implementing in about 18 lines of python.
Obviously there's dependencies to talk to the X server, but the power of a protocol comes from any program written in any la gage communicate with existing code.
Uh, do you happen to know where to find that project? Sounds pretty comprehensible for most people as an example.
Was a lot easier to understand for me than, say, dwm.
I had been using dwm (4000 lines of C) for many years and wished to write my own for a long time, but what made me take the leap was really steveWM [2] and TinyWM [3] which are both super small.
[1] - https://github.com/ChanderG/cellwm [2] - https://github.com/stodd1031/steveWM [3] - https://github.com/mackstann/tinywm
https://github.com/mackstann/tinywm
I've run it once a long time ago and worked perfectly fine for me.