There is some logic in what Asus is doing here considering the failure of the melting connectors.
If you have a 2 slot video card, why can't it plug into the 2 slots directly below it? (the second, only for power, but still there it is) It's simple and it does actually make a ton of common sense. If a 3 slot video card, why can't it plug into 3 slots? The fail is the proprietary slot in some regard. The other fail is that most motherboards don't place the PCI-e slots directly next to each other in alignment with the openings on the back of a standard computer case.
What is at issue, perhaps, is the power ceiling. PCI-e can only deliver what, 75w? You would need a ridiculous 7 slots for some of these 600w and up beasts going around these days. And they're talking about more and even more power consumption.