@jrgemignani
My thinking was to remove it from front face to encourage users to use stable platform (Rocky) because neither PostgreSQL nor the platform itself provide any update on CentOS 7 for quite sometime, and its not recommend for production use anymore.
Of course we can maintain a separate list with all support platform in documentation. ReadMe list neither cover our CI nor release testing platforms, but theoretically we do support all other distributions and platform which PostgreSQL support.

@sorrell dependancies are distro dependant, not package manager dependant.
e.g 'dnf` is same for RHEL 7/8/9, CentOS and Rocky Linux . But dependency list for all of them are different.

And I do agree we should combine distros, when/if dependencies are same. I am open to ideas.