Too bad Piotr Wozniak (inventor of SuperMemo) is such a hermit and uncompromising of his lifestyle choices, that most of his life's work was eventually superseded by open-source solutions (Anki + FSRS).
I had tons of material in SuperMemo for years. Gave up and fully switched to Anki.
At least I'm thankful for his spaced-repetition algorithms. Also, his articles restored my love for learning and helped me confirm that school was an insane waste of time and resources.
Last time I checked, Anki was nowhere near SuperMemo in regards to incremental reading features. Especially not with FSRS.
SuperMemo is actually almost the only reason I still keep a Windows VM.
But the whole Anki community is surrounded by his idea! Thanks for his effort; he makes learning possible for an uncountable number of people.