Oh I see what you mean. I was thinking of the asymmetrical situation where someone is putting out
unwelcome incivility eg 'you are evil and should die' or 'anigbrowl is an asshole!!! 1!' on everyone of my posts and then yelping about free speech when challenged.
All centralized forums eventually die (https://news.ycombinator.com/item?id=9867142), but that doesn't mean we should condone their locally-optimal actions while they're doing so.
Here we disagree (a little). In economic terms, when the platform is open and unregulated and anything goes, there is a large consumer surplus. People go to a centralized discussion platform because it offers some sort of technical surplus (ease-of-use, attractive appearance, social proof in the form of karma points or whatever) which they don't get otherwise. But as a platform becomes popular, there's a larger and larger cost in operating it, so you charge or add adverts or something. But now the people who are paying want additional value for their outlay over and above the basic consumer surplus, and usually that value is in the form of security from unwanted interaction, whether for their persona or their commercial brand. So for the producer to recoup the costs of operating the platform and reap some producer surplus from doing so (or why bother), the goal is to find a equilibrium between the degree of security provided and the partial loss of the original consumer surplus (of unrestricted communication).
Now it seems to me that this is a two-part thing. A site like Reddit dies a little if they institute behavior standards...but only a little bit. Trolls may leave altogether and the community becomes a bit more homogeneous, but then it can run for ages and ages. For example, people still log into AOL and many other moribund platforms - if there are enough people talking who are OK with the behavior standards it will keep going. What really kills it is the emergence of a new platform which offers substantial technical advantages in its turn (way better UI, super speed, brilliant new threading mechanism or whatever).
Because most of the effort on the new platform is technological, there may not be any behavior standards in place and so the first people onto that platform enjoy the freedom of saying/doing whatever they want, and the platform producers probably don't mind as they want to get people onboard to take advantage of the network effect. But only a percentage of the people are attracted to the new platform because of the behavioral freedom, whereas the majority are attracted by a combination of technical superiority and network effects.
I think Tor is a good example of this; you can fire up Tor and freely explore all sorts of contraband stuff if you're so inclined and not too paranoid. But if you're not after forbidden fruit, then the user experience of Tor is pretty bad (not due to some fundamental flaw of Tor, but the .onion ecosystem). The privacy benefits don't offer sufficient utility for most people to justify the awful UX unless you are looking for something very obscure (<5%) or just illegal (>95%). Probably 80% of the onion links I click don't even load, and since I'm not looking to buy drugs or criminal services exploring the .onion domain is generally a complete waste of time.
As far as decentralized protocols, "identity verification" is much stronger than what's needed and would be the path to madness (open to legal extortion, etc). What's essentially needed is a proof of work so that bad actors (whether one defines that as spammers or your standard youtube commenter) have finite amount of "energy", while nyms that prove worthwhile are unencumbered.
Oh, I was thinking more of the way that on 4chan you can post as anonymous and say anything you want or use a nym if you prefer. So if I thought 4chan cared what I thought and I wanted to get the credit for my brilliant ideas, I could post under my name. Of course on 4chan so can anyone else, so I'd like to be able to 'own' that name for as long as I am using it - not in the property sense but int he sense of distinguishing my authorship from imitators.