Isn't that exactly how these companies scale across multiple data centers? They write the code once, package it all together, and host it in multiple areas?

Getting back to games, I still don't see why allowing users to host private servers with their friends is impossible. If anything, it seems like its strictly a DRM issue...but at EOL for a game you no longer find profitable enough to keep the servers online, who really cares about DRM

Wat? E-trade is not an application, it's probably dozens of coordinated services. Meanwhile, a game usually has a single binary and another one for the server.