I too am frustrated by ancient versions of server OSs that use equally ancient versions of Python, but that's why virtualenv was invented. And source distributions. I am happy using it when required.
Being "stable" in OS terms is not changing APIs very often. One of the good things is that I know that code I wrote for RHEL 4 the day it was launched will run flawlessly on RHEL 4 today. The primary goal of such a Linux distro is that "it has to work". I won't touch the system parts.