Tell me about public blockchain apps that do not involve objective money or objective identity, which require strict global consensus, why they should be built on public blockchains, and why haven't they been built yet? I'll consider writing a post, when I get back to it, to explain why it does or doesn't make sense

Can you give some examples about possible public blockchain apps that require strict global consensus?

Everything that I can think of right now has some form of identity for achieving consensus.