I have absolutely no idea why you would think that an f3.5 lens means it would be a "crude triplet". The finest lens I have ever used for medium format is 6 elements and f3.5, for instance. If it were a Tessar to cover 6x7, I would be astonished if it were faster than f3.5 anyway. To keep the bulk down, even a more complex design simply isn't going to be any faster and allow for the folding design of the camera.