https://xkcd.com/1357/ makes it seem like it'll be your peers that get your message silenced, but what if it's some board of directors for a conglomerate, that dislikes any attention to the environmental impact of their industrial pig farms/how much they profited from post-war contracts after the most recent invasion/their push for privatization of water sources?
Almost all public speaking these days is done on private platforms, with ever fewer companies controlling them. Without them, almost no-one will hear you. The 1st amendment is just a legal codification of the broader goal of the free exchange of ideas. This goal is harmed by private censorship as well, even if it doesn't break the 1st amendment.