You're missing the point. Even if running a git server is easy, not everyone will bother to maintain it and setup a regular backup process. Also, where do you back that data up to? Some central server or DHT/BitTorrent. Inherently, AWS is popular because companies would rather pay to have someone deal with the headache of managing hardware and infrastructure.

> Why do I need a website to write to you? I can write directly to you, if both of us are on an IPv6 network.

Because I'm not always online and you might not be when I'm.