I do not see any advanced AI tools as a particularly serious threat to anonymity in online communications. We are well past that phase in the war on misinformation.
You seem to be concerned by the use of chatbots as tool for [political] propaganda, but it is Facebook, not 4chan that is the primary target for such large-scale campaigns. It is relatively trivial for state-level actors to fabricate online identities. Thus, placing citizens under strict online control would be truly Orwellian, all while troll farms would still thrive (and there's nothing to prevent a given government from recruiting actual, verifiable humans to post online!).
Trust is a core feature of human social interaction. Yet, it is easily exploitable, and one does not need advanced AI for that: stories of con men are countless, and modern media has mastered the art of clickbait. What differentiates AI from human writers is productivity and feasibility to mass-target a people exploiting their specific fears and desires... But I would argue that if someone habitually takes the bait, sooner or later they would fall prey to much cruder approaches anyway.
I am Russian, and I have friends, relatives and colleagues exposed to both sides of political propaganda with mixed results. The main differentiator between those who easily fall to things akin to QAnon conspiracies and those who don't is critical thinking. And a bit of digital hygiene, too, I suppose.
In this regard, the rapid progress in LLMs is merely a part of a broader issue that is ethics of social media and algorithmic recommendations. If the key metric is user engagement with the platform, how much is left of free will? Do people exercise it when following Siri's recommendations of what to have for dinner, what to wear, and how to spend their weekends?
The humanity has fought hard to bear the burden of responsibility for one is choices and the freedom to make them; now it is given away without much of a fight.
Going on a bit of a tangent here, but one other major thing we have lost since the Cold War, albeit not entirely, is the trust in public institutions and science/engineering as a whole. It would be much, much easier to fight misinformation online if people would refer to several authoritative, institutional sources instead of going with what their online friend pete93 has to tell them. After all, pete93 had a stunt 2 years ago working as janitor in NASA, they could not possibly be wrong!
Jokes aside, the main ethical question regarding misinformation online has to do with responsibility, and in my humble view, the part of the burden the general public can't bear should be squarely placed on public institutions with maximal transparency. More importantly, said general public has to accept more responsibility for being deceived than it does right now: it may be a malicious actor who sought to exploit you, and you might rightfully be wishing to live in a safe world where it does not happen... But this is simply not the case right now, and it hardly ever was throughout the history.
Things that help creating and spreading misinformation online:
- Conspiracy theorists
- Lack of education
Things that help fighting misinformation:
- Critical thinking
- Trust in public institutions
Things that do not help fighting misinformation:
- Biometric IDs online
- Thought policing
As @haxor798 has hinted at, linking every single account makes targeting people online actually easier, which, I would argue, would only serve propaganda makers, harassers and trolls. There is little to gain and a lot to lose here.
In contrast, providing better informational infrastructure, educating the public on matters of misinformation online and digital hygiene might alleviate the issue. After Montessori, I must repeat - "Establishing lasting peace is the work of education". And so is establishing safety.