Earlier quoted context omitted.
Twitter can have a very high signal-to-noise ratio if you follow the right people.
I followed a lot of economists (ie Robert Reich, Krugman, etc) thinking they would post interesting economics related content. They do, but it turns out that they are ordinary humans who like posting the same tweets (and rants) that I would post. I don't think Twitter can have the same signal to noise ratio as a well moderated forum like HN, even if you follow the "right" people, because the format of the site incent…
I think you have to stop following famous people like those guys, and instead follow up-and-coming economists and other scientists and bleeding edge researchers/builders, who are working hard to make a name for themselves with novel research in some interesting area.
Those are more likely to keep their Twitter feed focused on their research, rather than off-topic tweets, rants, political advocacy and "influencer" stuff people do once they become famous.
Also, the community of people who engage with them tend to be similarly focused, so you can find more high S:N folks to follow in their discussions.
If you curate your Twitter feed to just those types, you get a very high S:N ratio there.