True censorship is when government does it. If you go to jail for promoting some information, that's censorship.
Twitter and Facebook are part of "the public". You are even using right now a website very heavy on "censorship", or how I call it "moderation". If you don't follow HN guidelines you will be silenced. The efforts by members of public to reduce spread of misinformation and polarization is part of why we should trust in public to handle information. But if you do not like HN, Twitter, Facebook you can look for another website.
Apparently Parler is getting recently popular as an alternative to Twitter and Facebook moderation: https://en.wikipedia.org/wiki/Parler