If they use the common github approach of one fork per contributor, 6,000 repos accumulate quickly.

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?

It's common in general open source projects where you might want to send a patch for something that you don't have commit priveleges too, but I've never seen that used in enterprises as they have central auth / groups with the users required to work on the code.

I don't think that's a common workflow within companies. In every org I have worked at, forking is explicitly disabled

I worked at a large gaming company and that was definitely the collaboration model.

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.

You don't have 500000 garbage leftover branches on the main repo.

TFS converting to Git/Azure DevOps here. Be the change you want to see in the world! There's a chance that some of the people in your org that don't use TFS could use the organizational tools built into GitHub/GitLab/BitBucket/DevOps. If you get enough teams on board with that platform that also happens to use Git, then you can make that push to IT!

My company has way more than 6,000 devs and each dev creates a git repo as part of our onboarding process and uploads it to our centralized git tool (you create and push a mostly empty test repo as part of the basic training). Just from that, I'd imagine my company has tens of thousands of git repos, although a lot of them probably only have a single file or some random throwaway code.

The number of git repos might look big but without knowing more, the content of most of those repos could be a complete nothingburger. Number of git repos is pretty meaningless metric, IMO.

Note it doesn't say unique git repositories. It could just mean each employee's fork is included in that count, which would inflate the number like that.

Could include dependencies and forks of other public repos.