I’ve seen this mentality quite a lot online, and amongst a few of my friends, and I strongly disagree. One of the best things about the Internet is that anyone is free to create their own space and treat it however they want. The Fediverse is a natural extension of that idea, allowing anyone to make their own website and federate it into the larger community. But the community should be allowed to reject people. I wouldn’t tolerate someone who walked into my house and started arguing with me.
The community will naturally form spaces that are open to discussion, but I don’t think that should be forced. If the larger community agrees that there should be no outside discussion and you disagree with that, find a different community or make your own. Not all spaces are meant for everyone and that should be fine.
I recognize that larger communities build traction, but that can be disrupted (see Reddit / Lemmy & Twitter / Mastodon). I don’t think people will radicalize just because they push out people who they don’t want in their online spaces, especially since the Internet is so widely connected through federation, screenshots, link sharing, and even telling stories.
I don’t want to say that you’re not allowed to have your opinions and feel displeasure with the way Lemmy is moving, but I do want you to know that you can create your own community, either through your own hosted server or through a server that shares your worldview. The Fediverse is larger than lemmy.world and it’s up to you to find a place that you feel comfortable and accepted.
You can have multiple spaces in a community. Some for discussion, some not for discussion. You can also have different communities, some that allow discussion and some that don’t. To expand on the house analogy, if someone walked into a Star Wars themed bar with a shirt reading “Star Trek is the superior sci-fi show” and people got mad and tried to force the Star Trek to leave, they would be justified. That example is overly dramatic, but there are spaces online and offline where people want to enjoy or discuss a thing and should not have to be subjected to people who disagree with them. If some wants discussion, they can create a new space and advertise that space as friendly and open to discussion.
This post is a perfect example of being a space open to discussion. The OP wanted discussion and so people come in with that mindset. But if the OP said “What’s everyone favorite fruit?” and someone commented saying “I hate fruit”, that comment would not be appropriate for the post. It would be off topic and inflammatory and likely be cleaned up (removed) by a moderator. I know people believe that moderators can overreach, but those spaces belong to the moderators. If you don’t like how they police a community, find or make a new community.