This means that I can have a list of (for example) upcoming birthdays on my phone that I see over and over again, enough that I will eventually see the reminder at a point when I am in a position to do something about it. Alarms are useless by comparison, because I will inevitably be busy with something else when they go off. Calendars/todo apps are equally useless to me, because they require me to remember to open up an app all the time.
I realise my use case is relatively niche, but I imagine there's a lot of different niche users out there that benefit from customisability.
