Like it says in the man page, git add -p "effectively runs add --interactive, but bypasses the initial command menu and directly jumps to the patch subcommand". Interactive mode does support adding untracked files.
If you can't name a single protocol that is better at what XMPP does, don't you think "(lets face it) terrible" is a bit of an overstatement? It seems more like a "democracy is the worst system, except for everything else we've tried" scenario.