GitHub, for better or worse, has been one of the easiest ways to backup configuration for ..decades now. It's more secure than sending an email to yourself, Google drive still doesn't have an official linux client, AWS is too enterprisey for a handful of small backup files, and git is incredibly easy to set up + available on so many computers.
I completely get why people would want to use GitHub for a low friction way to store versioned configuration data. It's a natural case for programmers to use the tool they're already using for something else. There's even repos for dotfiles saying stuff like 'hey fork this and make it private' because they know people want to manage dotfiles but might lazily leak some secrets in their own versions
I don't know if I would say it is easy as much as I'd say it is automated. I manage configuration changes to some hardware using git, and do manual backup. However, someone else came out with a script that will automate periodic commits to a GitHub account, and automates the setup.
I have a linux distribution which gives the option to allow login via a set of GitHub usernames, and will enable so by downloading each account's public SSH keys.
I don't use either of these, I don't think the second is even a good idea, but can get why its popularity and price has caused deeper integration into products. Other network backup services or login infrastructure does not have the same level of ubiquitous API nor a relevant free tier.
I completely get why people would want to use GitHub for a low friction way to store versioned configuration data. It's a natural case for programmers to use the tool they're already using for something else. There's even repos for dotfiles saying stuff like 'hey fork this and make it private' because they know people want to manage dotfiles but might lazily leak some secrets in their own versions