The other reason is because it's the only approved distribution your company's IT department allows. Or the only distro your company's mandatory "security" software runs on. Etc. It's dysfunctional, but "enterprise" tends to mean "ancient 'stable' distribution if Linux is allowed at all" which in turn means "system python isn't useful, even if using it wouldn't break the system".
The other reason is because it's the only approved distribution your company's IT department allows. Or the only distro your company's mandatory "security" software runs on. Etc. It's dysfunctional, but "enterprise" tends to mean "ancient 'stable' distribution if Linux is allowed at all" which in turn means "system python isn't useful, even if using it wouldn't break the system".