This seems like bad advice. I've very rarely committed extra files by accident, but I would 100% forget to unignore files I meant to commit.
If you're doing an initial setup step to gitignore everything, why not just do an initial setup step to gitignore the usual files? Make a template that you copy into all of your repos.
If you're doing an initial setup step to gitignore everything, why not just do an initial setup step to gitignore the usual files? Make a template that you copy into all of your repos.