That's solving a different, and far easier, problem.
I'm perfectly happy setting up my Git repos on a fileserver I have to access via SSH. That's easy enough. It works fine. But it falls down when I want to share my code with my buddy, and now I have to make a user for him. Or suppose I want some code to be world-readable because it's not sensitive and I want to clone it onto VMs that I don't want to configure to SSH into my dev server. Or I want to put a sensitive repo behind some kind of authorization, and I want full read-write access to it, but I only want my pal to have read-only access.
You can do all these things yourself using standard Unix tools. I've done it. It's possible, but wow, it's way more of a pain in the neck than just installing Forgejo and saying "put repo A behind authentication, make repo B publicly read-only, and grant my clumsy friend read-only access to repo B (but allow him to open a PR if he wants to make a change to it)". Those are all real-world things I want to do, and Forgejo and friends are way easier to configure correctly than Unix permissions and a handful of SSH pub keys.