Earlier quoted context omitted.
I've never worked in this way (when I've been part of the org), is it that common? What are the benefits of making everyone fork repos vs branching off the original repo?
I don't think that's a common workflow within companies. In every org I have worked at, forking is explicitly disabled
Before per-branch controls, the only way to disable write access (while maintaining read access, pull-request privs, etc) to a repository's blessed branches was forks.