zlacker

Works well in some cases (eg some language learning patterns - but not all) but not in others. And even when you "create your own cards" you're usually using resources from elsewhere - eg native speaker audio on language cards.

A significant number of anki users (eg: medicine, law - others) are working with pre-made decks and if you look at anki's competition - all of them offer pre-made decks as a key part of it. Medics have always used flashcards (many university bookshops sell physical flashcards for medics) and I don't each medical student would benefit from producing, eg, their own anatomy flashcards.