Say you want to do meditation daily, but you don't want to track it (what Meditation Tracker does), but you do want to keep track of your streak. Or if you want to start reading daily. 1+1?
Say you want to make sure that you are doing it daily and on the days you are not able to, you are noting down the reasons, which you can visit later on to make sure you don't repeat the same mistakes.
This app can come handy in those cases, as well as the very obvious use case of addiction (could be anything).