[Ar-Curunir]

The evidence lies in the failure of the cryptographic community to provide a solution with strong security properties that is performant. For example, nobody has even attempted an ORAM-based database system. We also do not have schemes that can efficiently provide an intermediate level of security, between "weak" and "strong" systems.

Either way, as I said earlier, it's a question of threat models. Most cloud users trust Google and Amazon. These companies also have strong intrusion detection capabilities, so with non-negligible probability an outside attacker would be detected within a reasonable amount of time. In such a scenario, it is better to have some protection than none at all.

[swordswinger12]

The failures of the academic cryptography community to provide solutions to real-world problems in general are well-documented, and I will not belabor them here (q.v. Rogaway's "The Moral Character of Cryptographic Work").

I will only say that I don't think this problem (strong security + performance) has been on the minds of very many people for very long, and this work is really still in its infancy.