Decentralised is really the only option for an informed humanity. In the long run, this has to be the answer.
You need a minimum amount of moderation to remove the least desirable groups of people from posting content.
Not if police intervenes, at least for the pedos there exist established international relations between agencies that works efficiently - there is a reason why you won't see pedo content on the clearnet for long.
I would ask, where is the crime here? Is it that you saw something terrible, or that something terrible occurred? Should we be focused on the prevention of immoral acts, or the representation of those immoral acts on video?
Does your not knowing about certain immoral acts make it better or worse in reality for those suffering by them? If the reality is that there are racists and pedophiles, is better to address the issue openly, or behind closed doors?
In my opinion, it is better to enshrine freedom of speech, and to address issues openly. Having things 'managed' privately may mean that it is ok, as long as no one finds out about it. Its definitely a difficult one, but I am not for hiding reality.
Yes, technically it's not illegal to allow those kind of fringe statements but by doing so you implicitly allow that content to rise to the top and it can make your site unsafe for racial minorities and children.
We elect government democratically, and through that create laws and police. If the internet is full of criminals flaunting laws then the problem is right there in the lack of laws and police, not in the lack of control from a small group of companies.
There is only one Reddit instance. Subreddits may have quasi-independent moderation (Reddit admins can always intervene if not doing so would cause bigger PR problems than they're willing to ignore or deal with in other ways) but there's no real way for one subreddit to disassociate with other subreddits.
PeerTube (or Mastodon or PixelFed or Lemmy) instances can disassociate from other instances that have incompatible moderation practices, though. Either through allowlisting or denylisting depending on the operators' risk models.
Using Mastodon as a case study: Gab tried to pivot to ActivityPub-based software (I think Mastodon) and yet they were denied the ability to federate with most instances because it's a deeply toxic community.
ActivityPub is federated and has moderation pretty much built in by design.
that implies that "an informed humanity" is something that society wants. I really doubt that.
The reality, is that 'society' is made up of individuals. Individuals are substantially real. Individuals need to choose for themselves whether they want to be informed or not, according to their conscience.
Individuals should also step out of other people's business, ie stop trying to manage 'society'! But that's another story.
Myself and a few people are actually working on a video site with freedom of speech values and grandma level usability, feel free to follow along (https://project49476.com/).