The short answer is that Chatter Net routes messages to you only from people you follow. If this was just messages authored by people you follow, it wouldn't be a very interesting platform. But in fact, whenever a message lands on your UI, you emit a View (https://www.w3.org/TR/activitystreams-vocabulary/#dfn-view) event on the message you just viewed. And so people who follow you will see that view, and that's how content makes it way around.
The long answer is.. well long. And it's not an answer so much as a conversation. I see this as all relating to trust. And it's not really possible to discuss trust without implicating the debate of anonymity vs. privacy.
In real world communities, you trust some people, and so you are wiling to spend time listening to them. These could be family, friends, actors, politicians etc.
On the internet, the mechanism for trusting someone is actually a bit odd. You believe that when you connect to a known domain, there is some trustworthy entity behind it serving you content of interest to you. And if that domain hosts a social media platform, and that platform trusts a user by allowing the user to create an account, then you sort of extend the trust you have in the platform to that user. But this is all very anonymous and leads to all sorts of issues such as bot farms and domain parking.
When things are framed that way, it almost seems the current efforts around moderation are really trying to treat the symptom, not the cause. Does it make sense to trust an anonymous user on some platform? The place this seems to work best is Wikipedia. But even there the implicit trust in user accounts is sometimes abused (https://www.theatlantic.com/business/archive/2015/08/wikiped...).
I think somewhere along the line the concepts of anonymity and privacy got confused. In the real world, if you walk around hiding your face and otherwise concealing your identity, people don't trust you. The things you want to keep private, you discuss in a private setting (e.g. in the comfort of your home). But when you are in a public forum, your identity is what you use to get others to listen to you and interact with you.
In this sense, Chatter Net is a public forum, while something like Signal or Matrix Chat would be a private forum.