You forgot to mention the "click on this one specific checkbox or your source code is now leaked to the entire internet forever" part. So actually, not that simple and potentially much much worse.
Git != Github
Just using git on a local machine is nothing like this, unless there's something large I'm missing.
You could also use git-send-email to make a mailing "list" with just yourself, and that way make it much easier to move between machines as you work. Or if you don't trust your email hosting provider, self host gitea or sourcehut (or have the option to later).
Finally, you also get the ability to better organize development with branches.
I don't even know git that well and came up with that off the top of my head.