Looked to me like blocking caused the wreck. If there was no block, then there wouldn't have been contact between the #2 and the #22.
The real question is "what causes the blocking?" Is NASCAR getting what they want? There are NO penalties for blocking, even when there's a high percentage that it is going to cause a wreck, so I'm no expert, but I would expect more of the same. It's been that way for quite a while and I think NASCAR has decided that they need "the big one", and not having a blocking rule ensures that they'll always be at least one big one, especially when it comes down to the money lap.
If you were the leader, would you block?
If you were in second, or had a run, would you lift?
I watched the balance of the race today the #34 and the #2 make their move to the left, and a fraction of a second later, the #22 makes his move to the left to block. At that point, the #2 tries to go right, and..... well... just watch Fox Sports for the next week to see them play, and replay... and replay... and replay what happens next.