Example: I want to set up a forum where people can discuss a specific topic. Such as the Arch Linux forum, or ones for vehicles (https://www.ninja400riders.com/, https://www.civicx.com/forum/). I am clearly not a publisher; I do produce content and do not want to produce content. So I am a platform.
Am I no longer allowed to decide what is acceptable on my platform? Even if I am running a forum about the Ninja 400 motorcycle, I now have to allow people to post about their Toyota Corolla or about how vaccines cause autism or the earth is flat? What about if I want to moderate the forum to keep discussion on topic and I need to delete trolling or spam, or lock/delete threads that devolve into political fighting among forum members?
You can't have platforms without moderation.