Social media are not publishers. They are way more public squares, but online.
On top of that, even when publishers usually curate content, there is no obligation to do so. It's just something that has been done, because publishing used to be expensive.
Now, when sharing data online is cheaper and cheaper, this limiting factor is fading away.
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At the same time, we have just 16 hours of attention per day. So you have to decide whether you want to invest your time in more curated publishing (I read a lot of books, often old books which stood the test of time), or if you want to go to the public square where practically anyone can shout as he sees fit. I do that too, but I try to moderate both my time using social media and what I see there. And I am proud I haven't used TikTok, I stopped using Facebook, Instagram, I don't watch any Reels, Shorts, etc.
So publishers still are not lost, but what they are selling is not curation because of technological limitations, but because of limits of how much we can read and see in the day.
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At the same time, publishers are biased. They publish what they see as high quality. They publish what they consider worthy. They publish things they would want to read. And they have publication checklists that prohibit publishing certain things even if they are true.
Public squares don't have such an attribute.
There are things to be published and heard, even when mainstream people would disagree.
There are things that should be public, even when it's against a law in certain countries.
And online anonymity mixed with public square enables people to tell about atrocities that happen, or about corruption, government inefficiencies, about people breaking human rights and so on.
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If you end anonymity and public squares, you end a channel for democratic feedback.
Because publishers don't play this role any more. They are biased, people realize it and are fed of it.