Why yes, you happen to be correct. It can be done with cat and grep, and really you can do it without cat! However, it's perhaps desirable to be able to do thin

Why yes, you happen to be correct. It can be done with cat and grep, and really you can do it without cat! However, it's perhaps desirable to be able to do things like edit the todo/tofix, delete them, export them to your todo application of choice, etc, etc, etc, etc. So, while you're correct in that you certainly can do it with grep, you're severely limiting yourself if you choose to.