Comment by ryanbrunner

The problem with this approach (that their first example already demonstrates), is that you'll almost immediately start with a "this type of file is OK" solution, and whether something should go in git doesn't really have a super strong correlation with file type.

It hobbles `git status` and essentially forces you to keep track of what you've changed yourself (since ignored files won't show up there), and it can instill a false sense of security that `git add .` is safe when it might not be.