Then who provides security and bug fixes for that snapshot for the ten years during which a RHEL version is supported? EPEL is basically what you're asking for, but limited to packages where someone is willing to make that commitment.
"RHEL 6 was first released in 2010 and there's still Python 2.6 on that"
Or Python 2.7 or 3.3 can be installed via Software Collections. These have a predictable release cycle- a new version is released every 18 months, and each version is supported for three years.