The only thing that makes sense to me is that the card manufacturers are repurposing production yield fallout, cosmetically defective or repaired cards. To incentivize this card, it would have to sell for $100 or mine at like at 60 Mh/s @ 50 watts.
That is what they did for the 1070ti now that it is known they were going to be using these chip cores for another card but didn't want to and just to save money created this ti version instead.