It is much easier to create large numbers of cards on desktop than mobile. There are also a large number of third party add-ons available for desktop https://ankiweb.net/shared/addons/
It is actually much easier to use a desktop browser as well. Yet, most traffic now is mobile.
Flashcards are a mobile usecase, I actually think a desktop version is actually limiting for them...maybe that's why Supermemo never became a roaring success.
