I personally don't get the obsession with changing everything to decentralisation, since it isn't something that needs to be implemented into everything, in fact I tend to believe in certain situations, decentralisation is a horrible idea.
I agree with you, people wanting to decentralize everything are either ignorant or just a dreamers who don't know how things work in real life.
Decentralized Bitcointalk would be terribly slow and unusable, but I would like to see certain parts of forum using decentralizations, maybe for some kind of voting, or things related with Ban/Unban.
This is not easy to implement, and I am almost certain this could not be implemented correctly in current bitcointalk forum software.
As much as I like the idea, there's a reason I haven't seen any real decentralized forum. The cons don't outweigh the pros.
It's not impossible to make it, maybe based on something similar like Tor, but everyone would probably have to download everything, and I am not sure many people would do that.
I know some decentralized forum attempts, but they never were 100% decentralized and they never got more attention or popularity.