alt Hacker NewsQuizzes had like an 85% engagement rate on Facebook, they were legendarily effective paid eyeballs content. Adtech firm System1 aka OpenMail even merged with an adtech firm that owned a quiz content company, it made like $1m/2wks at small scale. I don't really know what Cambridge Analytica concretely did (to this day I have not seen a single screenshot of any of their creatives or a single concrete report of theirs) but I do know quizzes were really effective. For whatever purposes.
Yes they had a high engagement rate (due to how the platforms were structured at the time and how hyper-shareable it was) and you could make some money serving ads on quizzes because they had a high engagement rate. They were absolutely terrible as an ad targeting methodology.