Python is not mandatory for Linux, and there are plenty of small "embedded" Linux systems that don't have it.

However, many distributions require it. So RHEL may have a dependency on Python because some of their management tools and scripts have been written in it. On those systems python is a requirement.

It isn't necesarry in terms that the system won't function if it isn't there but some distros have tools that are written in Python.

Anaconda, which is the installer for RHEL, CentOS, Fedora, Oracle Linux, and Scientific Linux, is written in Python as are yum and dnf which are the package managers.

portage, which is the package manager for Gentoo, is also written in Python.