At some point in the past I believed quiz type floodgates may be useful at some (early) stage. I probably though so when the forum was thriving with spam (even after the Merit System was set in motion), but interesting as it may seem subjectively, objectively it seems:

- Easily cheatable: There can only be so many questions to a Quiz on a given topic. Even if you randomize the questions, eventually the will end-up in an external document or database (by crowd-reporting of the questions) and made accessible to all, defeating the purpose.

- The idea of a forum having mandatory quizzes taken at some point seems like an overkill. One thing is taking a quiz for fun, but another is having to do it at some stage/s as part of the procedure to participate in the forum.