Can you still comment if you get all the quiz questions wrong?
Imagine an article on vaccinations--many who would be posting exactly the sort of nonsense you'd be hoping to prevent would wear their "understood 0% of the facts in the article" as a badge of pride, and others who agreed with them would interpret it as such.
I would not want to participate on such a platform forcing me to double check if my contributions were actually published or simply hidden away for some secret reason.
It's these pieces of accountability that go a long way to have users compliant with moderation.