Something which was trumpeted early on, but then later has been systematically neutered by Nvidia: is the potential flexibility of multi-gpu setups. A person might buy a 1060 right now. Because its perfect for them. or because its what they can afford. or whatever. But a year from now, they might find a good deal on another and wouldn't it be great if they could do that. At that point, who cares about performance scaling or games compatibility or well you shoulda just bought the $400 card a year ago... ...forget all of that. It used to be an option. I did it, once. Bought a couple of dell system pull 6800 PCI-E, to side-grade from my single 6800 AGP.
I agree with the last part. I have done that in the past. But I lost faith in dual gpu setups a while ago and I don't even bother about it. Its just never works the way I always hoped it would lol and the experience wasn't there for me. Mostly frustrating. I don't disagree with your suggestion because that is very tempting and I have done it before. But I think multigpu has sort of lost its interest other than benchmarking. I have seen more people suggest against it than for it. I myself has been victim of its frustrations lol.