Isn't private blockchain really an oxymoron? And a public blockchain really needs some method of funding/reimbursement --- like cryptocurrency. Otherwise, why would a "community" devote resources to the overhead of a blockchain? Without significant "community" resources and commitment, a blockchain can lack trust and thus start to wither and die.

In other words, aren't the "social engineering" aspects of a practical blockchain just as significant (if not more so) than the technical ones?

Aside from a few niche areas like cryptocurrency, isn't blockchain really a solution in search of a problem?