Where does this fall down?
That could be considered only a risk if the moderation is bad, but bad moderation becomes more likely over time due to feedback loops. An optimally permissive moderator will risk inviting an overly strict moderator due to that permissiveness. An overly restrictive moderator will not. There is a greater likelihood of moderation becoming increasingly restrictive over time because the moderation narrows the pool of moderators.
Anyone cuts up rough, I go by their house and make them miserable.
If someone gets to pick who's allowed onto a network, then they won't bother using it. Maybe your friends will join since they are allowed to add _their_ friends, but those friends of friends wouldn't bother because most of their friends can't join, meaning your friends won't bother either unless they really want to talk to you specifically.
It would work for groups where most people know each other, but there are already options for that that allow users to be in groups that aren't all owned by the same person e.g. Discord, Signal, Facebook.
But I see room for that. I would prefer it for kids until they reach a certain age so they can decide themselves. Given, I would have a lot of requirements for the identity provider. This requires a lot of trust and I don't really see many on the horizon here.
But universally for the net it would be a huge setback. It would end up like TV and interactivity isn't the only reason it got less popular.
i.e. illegal or fraudulent content is clearly owned by the user irongoat, and you know who irongoat is (at least you know their email, IP address) but no-one on your site knows who irongoat is.
If the content is bad enough, authorities will get in touch for you to tell them what email address irongoat is associated with.
But as long as the content is OK, irongoat can say what he/she wants, with no PII visible.
2. The politically, economically, and/or socially disadvantaged are further disadvantaged under such regimes. Yonatan Zunger, chief architect of Google+, put that quite clearly: "In practice, the forced revelation of information makes individual privilege and power more important. When everyone has to play with their cards on the table, so to speak, then people who feel like they can be themselves without consequence do so freely -- these generally being people with support groups of like-minded people, and who are neither economically nor physically vulnerable. People who are more vulnerable to consequences use concealment as a method of protection: it makes it possible to speak freely about controversial subjects, or even about any subjects, without fear of harassment."
https://web.archive.org/web/20180903205908/https://plus.goog...
3. Laws and regimes may change. Ask the inhabitants of Germany circa 1933, or those of Afghanistan circa 2021, among numerous other examples.
4. Groups themselves can lead to and engage in destructive activities. See the case of Reddit's increasing problems with brigading and other hostile activity amongst subreddits, resulting in the banning of numerous of these.
5. The consequences of a toxic media landscape at scale are felt by those considerably removed from the platform(s) themselves. Twitter cheered the Arab Spring protests. Facebook are attempting to distance themselves from their very active role in the Myanmar genocide. History shows that changes to media landscapes are often very disruptive socially and politically, often at a horrific cost of innocent lives.