RE: Tauchain may allow for the development of the first "Smart Constitution"
On the topic of filtering speech this in my opinion is what collaborative filtering can best handle. Filtering basically isolates the noise (what you would subjectively interpret as obscenity) so that it is not brought to your attention. So yes you can filter just fine and probably far more effectively with something like Tauchain because you could unambiguously and precisely define exactly what you consider to be the noise vs what you consider to be most valuable (and prioritize accordingly).
The point is you will not have to worry about contradicting yourself, or for example the situation where a person claims they believe in absolute free speech under specific conditions yet they don't because they don't vote in that manner? If you believe in absolute free speech then what is obscenity? Obscenity is the speech you don't want to see, the information you don't want to consume, the spam. Ideally no one should be forced to consume or see information they consider to be noise.
Collaborative filtering makes a lot of sense but carries a risk with its propensity for creating bubbles, isolation, and echo chambers. Filtering out everything you don't like can make for a peaceful experience, but in as much as online life is now strongly influencing the real work - to the point that it definitely affects elections now - it leads down that path towards one of those Black Mirror dystopia.
People have a propensity to be afraid or wary of things they haven't seen before. It's a vestigial survival skill that manifests itself in xenophobia and irrational dislike of things we have no experience of. I'm sure if you moved someone from 100 years ago to present time and plonked them down in a big City they would freak out at what they see in terms of diversity, dress, social norms etc. But given time I reckon they would adapt - just like someone coming out of the Amazon or a remote tribal life. However if you just shut out the rest of the world you're never going to change. You're never going to think gay marriage is okay, or back in the day that women or non-whites should get the vote, you'd never hear or see their voices and opinions. You'd never know that a clear majority of Americans think marijuana should be legal. You'd probably never know anyone that had come out. You could be just stuck in your community filtered bubble of fake news and very narrow opinions that would almost always agree with yours.
That's what I'd worry about...
Dystopia is caused by other problems which I address. It's not enough to give every human a vote if people aren't allowed to be wise. Social media doesn't encourage wisdom building, or good decision making, or knowledge diffusion. Social media encourages people to make critical decisions such as who to vote for based on stuff like party loyalty, or conspiracy theories, or gut feelings, so we don't have a situation where people even vote in their self interest.
Risk literacy tends to be low in people. People cannot assess risk very well but then are asked to make important decisions involving risk. Making decisions under uncertainty is about analysis of statistics. We aren't all going to be experts at that but maybe on a platform we will want to follow the people who are.
When faced with newer and better knowledge the correct thing to do is to update your worldview. This is a simple rule which could be implemented (if you think of it like a rule). This is called belief revision in the literature.
The point being that humans are too limited in ability to analyze information. Information is all around us and goes to waste. We also work with inaccurate models of reality which functions to keep us from acquiring or building wisdom. If wisdom building is as important as wealth building then we should want to build it but there isn't any reward for being wiser.
In other words ignorance is rewarded often and the forces of behaviorism are at play. The positive reinforcement, the intermittent reinforcement, all are involved at locking us into inaccurate models of reality and keeping us involuntarily ignorant. So of course when it's time to make critically important decisions we decide like we would a beauty pageant, or any other superficial contest.
Collaborative filtering is really the only way. The best we can do is make each individual a better thinker and decision maker if they choose to strive toward it.
References
I don't see how collaborative filtering fixes any of the issues you and I mention with social media. If I create an account on Netflix and select even one conspiracy theory or junk science documentary I'll be flooded with recommendations for like material my supposed peer group has collaboratively filtered for me. And the more I watch the more I will find. I would posit that life gravitates to local minima surrounded by inviting does lying the unselective in. These insular swamps stagnate and self enrich creating their own ecosystem and cultures. The human propensity for social activity makes it hard to escape - I've talked to many former members of religious cults (which is about all of them IMO) and they relate that first hand.
The current culture of treating knowledge and critical thinking is a depressing trend and stinks of rank centralised control. It doesn't give me much hope can shake up the playing field and and bust out some people from their festering puddles, pools, and swamps of circular and unreasonable thinking.