One trouble is that it's much faster to create fake news than to shoot them down with evidence. And as we have seen (for example with conspiracy theories), som

One trouble is that it's much faster to create fake news than to shoot them down with evidence. And as we have seen (for example with conspiracy theories), some people refuse to believe no matter how much facts you try to throw at them. With centralized platforms we might be able to still block the fake stuff and discredit people who post junk, but in decentralized world this will be impossible. People choose who they follow and to which fact checking service (if any) they subscribe.