Well, just a created date stamp won't be enough always. I want to record an event that occurred on a particular day, a few days after. In that case I need to change the date of the entry. Also if I want to check the incidents on a particular date, I need a calendar. All these are needed when using Evernote as a diary for recording events. Removed my email, thanks.
Diary notes apps like diaro, journey etc include a calendar.