I completely agree with you that Twitter is playing a casual role in the degradation of discourse within our society.
Go to the popular Twitter feeds and there are very obvious bot posts trying to scam and manipulate people. Twitter has not managed to stop them. Elon Musk's twitter feed is a great example of this. It even has the bots pretending to be him.
Here, if you want to appear popular and have greater ability to manipulate people, you can buy some followers: https://devumi.com/twitter-followers/ Now regardless of your worthiness you have social proof! Advocate for the lack of existence of a round earth to your hearts content, now with greater effectiveness.
The spread property of news on Twitter favors falsehood over truth: https://www.businessinsider.com/mit-study-fake-news-spreads-... This fact when combined with medium as message https://www.litcharts.com/lit/amusing-ourselves-to-death/cha... leads to a system which actively promotes the wrong sort of content. Clickbait is a reality, because clickbait gets clicks, so people write clickbait titles. The existence of the rules like those Hacker News has are a fight against these forces. This community was built in part with an understanding that these forces are real and harmful to discourse.
Twitter meanwhile has better engagement metrics by not solving these problems. So don't expect them to change, without any effort on their part. Fighting your own incentives is very hard. Twitter is basically addicted to harming discourse. Obviously, no ill will on its part, since this stuff wasn't obvious early on.
It has benefits too though. Like getting to hear the perspective of the people in question, without intermediary.