Well, it's an alternative for people who are looking for interesting, useful flashcard apps and found Anki limited or hard to use. Would you say Windows isn't an alternative for Linux?
No, it should at least mention "a paid alternative". E.g. one would say LibreOficce is a FREE alternative to MS.
Anki already is an alternative to SuperMemo, so a proprietary alternative to Anki doesn't make sense unless it somehow improves over SuperMemo.