It has been crazy since before apps were 'apps.' It is a simple flow chart to me: do I need to interact more than once a month? No? Should probably be a website. The only time I want an app is for things I check more than 50 or so times a day, but that is because the UI for phones is awful and it is more convenient to context switch. Needless to say I find messaging apps to be the only ones that qualify.