Many folks add events to their Calendar app on their iOS device the same way they’ve added events on paper since the way back days before smartphones and personal information managers. They flip to the date they want to add an event to, tap on the day, and then add it there.
This works, yes, but it can get tedious, with all the arrow tapping. What if your event is a couple years out? Even in month mode, tapping through 24 months is bound to get tedious.
There is, of course, an easier way.