I tried hosting a homebrew tap, after hosting apt and yum repositories.

That was when I realized Homebrew is much, much harder.

Your server needs to implement the git protocol. You can't just stick it on some server with a CDN in front of it, you need to run and fortify a git server.

Strange choices IMHO.

I think it is focused on GitHub. It might not be suited for many people this way, but it works well. Opionated design.