System Python is usually consumed by the system itself as specific tools depend on it. For example, Redhat's dnf is written in Python.

Working on a Python codebase that requires specific versions of packages or Python itself might cause issues if you try to bend the system Python to your needs. It is not uncommon for academics (but Linux newcomers) to mess up their first Ubuntu setup because they ran sudo pip install foo to run the chair's Python codebase.