Actually, it's more like saying, "we HIGHLY recommend having a backup parachute" (as, I'd imagine, most skydiving instructors would).
Also, I think I've always mention it in my talks.
I'm not sure how VoltDB escaped your wrath, it's an in-memory db that claims to be durable.
if you want to see a message that is clearly delivered about (lack of) durability look at memcached. nobody misunderstands memcached's durability/consistency guarantees.
-Mikeal (after a few drinks)