The key problem is social media feed boosting “engagement”. Balanced, well thought comments don't bring much engagement so they end up being ignored by the algorithm while outrageously stupid takes generate a lot of (negative) engagement, some of which being equally stupid which will bring more engagement than the sensible responses and so on. And at the end if the day, all you see in your social media feed is stupid people sharing at least some of your values arguing with even stupider people (or so you think, at least) who have the opposite views.

This is obviously harmful for society but also obviously the best outcome for the platform who wants to sell your attention to advertisers.