> It lets you debug.
It lets you debug Python problems which the system created in the first place.
> If they have some weirdly screwed up paths with multiple pythons installed and multiple copies of the modules etc., same.
Doesn't happen in a sane language. Or, even not a sanely defined language/implementation.
I can easily have multiple different GCC copies (possibly for different processor targets) on the same machine. Each one knows where its own files are; an #include <stdio.h> compiled with your /path/to/arm-linux-eabi-gcc will positively not use your /usr/include/stdio.h, unless you explicitly do stupid things, like -I/usr/include on the command line.