> You should not be relying on system installed interpreters
No one seems to have a problem with that if it's bash.
You definitely shouldn't be willy-nilly modifying the environment of system interpreters, but relying on them for ops-like uses and bootstrapping dev environments is sensible.
My understanding is that Python break backwards compatibility (or forward compatibility) comparatively more often than bash. The problem with OS interpreters is entirely linked to stability and portability indeed regarding bash, many suggest to avoid bashism as much as possible and be posix compliant.
No one seems to have a problem with that if it's bash.
You definitely shouldn't be willy-nilly modifying the environment of system interpreters, but relying on them for ops-like uses and bootstrapping dev environments is sensible.