Another issue is, how do you get your games when you're banned? Most people don't have all their games installed at any given time.

With GOG, there is at least an unofficial, supported way to get an offline installer for each of your games. With Steam, there's no officially supported way to do this, so it's likely to be a bigger PITA to archive all your games ahead of time.

In reality, though, almost nobody is thinking ahead so that they have all their games archived, and, given the size of games and collections, it's a difficult thing to do on the cheap.