Earlier quoted context omitted.
Git isn't generally configured to automatically upload your files as you type or as files are saved. There are things like GitFS, but I imagine those aren't part of an average developer's workflow.
My point is that an inexperienced Git user can push their secrets to Github for example, just like a Kite user who doesn't specify a .kiteignore.
If I'm testing an app and I want to hard code an API key for testing, and I'm using Github, it's not a problem. I have to explicitly commit that file. Now, I have to both remember that Kite uploads everything, and avoid using that workflow at all, and use the .kiteignore thing (which is another random dotfile in my repo, great).