HN could allow the submitter to optionally configure up to 3 multiple choice questions about the article.
A user would need to answer all of them correctly before being able to comment. An incorrect answer would add a delay of ~1h before they can comment (without needing to do the quiz again).
Even though it’s fairly easy to cheat or work around, it might be enough to tilt the incentives towards just reading or at least skimming the article.