In particular, re: "Nobody serious says that decentralization == privacy" -- this is presented as tautology on regular basis, by people that certainly hold themselves as serious and I'm willing to take as such, on Hacker News and other IT-related forums, as well as many other venues.
"Are people suggesting that new economics are needed? I don't think most people are suggesting that" - a lot of more zealous cryptocurrency supporters are very much on the "this is like nothing we've ever seen before" bandwagon, and/or are explicitly desiring as a goal/hope a massive disruption of economic and financial systems.
Just like, if there are N Christians, there are in my experience N+1 Christian belief systems, so it appears to be the case for cryptocurrencies. People more patient than myself are trying to make a dent by tackling those N+1 arguments, hopefully cognizant that for any set of believes P, they'll be presented with those exclaiming set of beliefs Q which obviously has nothing to do with P, those people into P are deluded/irrelevant, and they would never agree with them (unless it offered them temporary advantage:).
I think maybe you're reading them uncharitably. Decentralization does enable privacy. But it isn't identical and equivalent to it.
That's a mantra I've heard non-stop for as long as I've been paying attention to cryptos.
To be fair, though, I hear it almost exclusively from the evangelists and traders, who have an economic interest in pushing that narrative.
Are people suggesting that new economics are needed? I don't think most people are suggesting that. They are suggesting that blockchains allow you to implement economic incentive schemes that weren't previously feasible.
> Privacy. It's often taken for granted that decentralized architectures will improve privacy. This seems obvious given everything we've learnt about Facebook, but a better way to think about it is that decentralized systems exchange one set of privacy problems with another. I coauthored a paper a few years ago skeptical of the "decentralization ==> privacy" story in the context of social networks [3], but I think many of the arguments in that paper apply to blockchain/dApps that are being built today.
Nobody serious says that decentralization == privacy. However, decentralization does allow you to to implement strong privacy systems, like Monero/Zcash.