Picks any two of these three, I don't believe it's possible to do all three: 1. Decentralised 2. No Spam/manipulation 3. No censorship (The boundary between what is classed as manipulation, and what shouldn't be censored will never be solved)
No censorship doesn't mean everybody has to be forced to read your crap. People should still be able to block assholes. If you think that that's censorship, then it's your "no spam" and "no censorship" requirements that bite each other, and decentralisation has nothing to do with it.