I wouldn't say anyone is arguing big men are obsolete, only that you have to be able to space the floor, and occasionally go small. SA is terrific at both those things, in part because their big man is maybe the greatest PF ever to play, and he developed an effective 10ft and out game, plays small ball C and is a terrific passer.
With the sixers the problem so far is that they invested 3 top 3 draft picks in big men who can't space the floor, and all 3 are really 5s, and are less effective at the 4.
That means in a best case scenario (Embiid comes back and is good), they still need to trade at least 1.
I understand the thought process of BPA, but I don't think they were clear enough BPA to draft guys Hinkie should know can't effectively play together. I don't see any combination of those 3 that works. None of them space the floor, and none of them defend the 4 that well (Noel isn't that bad, but he's very good at the 5, so it's a waste to make him an average at best defensive 4, especially since his offense is poor.)
Let me give a counter drafting strategy based on who was projected as possible picks in Sixers spots.
2014- Exum/Smart/ Keep Payton
2015- Porzingis
That would be to me a much better base for a team. You have young real talent at guard and in the frontcourt, a much better defensive team, but not going to win so many games as to hurt the draft options this year. Most importantly all those guys can easily play in the same rotation. Maybe eventually you move one of the guards, but you don't have to, they have enough size to play as a backcourt together.