It seems rather harsh to brand them as pure snake oil based on a hypothetical situation that applies to basically every single piece of software and hardware ever invented, but fair enough.
I like to see it as an unsolved problem. Similar to when Diffie and Hellman revolutionized cryptography with the concept of public/private keys, I like to think that one day, a revolutionary proof will drop that demonstrates a true trustless privacy model where backdooring isn't even a remote possibility.
I suppose you always have to trust someone. (I'm not the one who branded them as snake oil, BTW)