RHEL 6 uses python 2.6, and is supported till 2020 (not counting the extended support). Of course, if an app only needs a single host or two, its no problem to have an updated OS for that app. But certain app types, such as backup and monitoring apps, don't do any good unless they run on the majority of systems that a site has. In my case, I couldn't even try out several popular backup systems, as they either required Python 3, or had other library requirements that weren't available on the older enterprise systems.