I don't see it as so black and white. Sure, zero trust is the ideal, but there are potentially benefits even there's some trust involved. For example, I saw a headline indicating that Unicef was going to experiment with block chain technology and asset management. Charity strikes me as particularly suitable domain since benefactors are understandably concerned about how their donations are being used and there's little need or even desire for secrecy. Block chain could provide an unparalleled degree of transparency and accountability even if the humans in control of the private keys ultimately need to be trusted. "Trust but verify" as Reagan said, and it would help a great deal with the latter if not the former.