Simply asking for what value has Bitcoin et al provided isn't the same as a statement that states it doesn't cover some areas of value, however pros existing doesn't necessarily negate the cons - doesn't mean there's a net benefit to them existing. Ignoring that a solution for 'trust in decentralized networks' can't be solved in other ways, like normal real-life trust networks, where people make a decision of who they trust for this vs. having "blind trust" is in fact blatant ignorance.