I agree with every word of that.

For listeners at home wondering why you'd want that at all:

I want a centralized Git repo where I can sync config files from my various machines. I have a VPS so I just create a .git directory and start using SSH to push/pull against it. Everything works!

But then, my buddy wants to see some of my config files. Hmm. I can create an SSH user for him and then set the permissions on that .git to give him read-only access. Fine. That works.

Until he improves some of them. Hey, can I give him a read-write repo he can push a branch to? Um, sure, give me a bit to think this through...

And one of his coworkers thinks this is fascinating and wants to look, too. Do I create an SSH account for this person I don't know well at all?

At this point, I've done more work than just installing something like Forgejo and letting my friend and his FOAF create accounts on it. There's a nice UI for configuring their permissions. They don't have SSH access directly into my server. It's all the convenience of something like GitHub, except entirely under my control and I don't have to pay for private repos.