You're completely right. Having an understanding of the topic is important. In fact it's stressed on our "Making flashcards" guide: https://zorbi.cards/making-good-flashcards

It's mostly the convenience of always having the ability to create a spaced-repetition flashcard there in your browser.

Our primary use cases are studying for exams and language learning. Hopefully that sheds some more light on how the Chrome extension / Notion integration are used.