when it's the default editor and you go to add a cron job...

From the git documentation:

  *core.editor*
  
  *By default, Git uses whatever you’ve set as your default text editor via
  one of the shell environment variables VISUAL or EDITOR, or else falls back
  to the vi editor to create and edit your commit and tag messages*

  https://www.git-scm.com/book/en/v2/Customizing-Git-Git-Configuration

It seems that many people leave their default editor undefined so git opens vi for commit messages by default. vi tends to be symlinked to vim on many systems so that means they end up in vim (not that it makes a difference, I'm just being pedantic :).

As a complete vim beginner this is what I did and still do. I have never opened it fresh as I don't know how to then open a file :D