I don't know if you've tried to get someone else's Python running recently, but it has devolved into a disaster effectively requiring containers to accurately replicate the exact environment it was written in.
Core system applications should be binaries that run with absolutely minimal dependencies outside of default system-wide libraries. Heck, I would go as far as to say applications in the critical path to repairing a system (like apt) should be statically linked since we no longer live in a storage constrained world.