I wrote my own app as a fun project and as a way to look at how I could make a flashcard a better user experience overall. The daily overdue experience was just one thing that I didn't like.

I think Anki is powerful and has a lot of configuration settings and add-ons to support new scenarios, but I think for a lot of average non-technical users, they may be overwhelmed by that and not interested in learning it. My goal was to write an app for those people (and for me).