To get access to the Hadoop cluster you also needed special permissions and to go through a committee. At Facebook, access was given to all technical and non-technical (after an afternoon of training) people.
Sure but you went through the committee once and then had as much computing resources as you needed. I don't remember it being hard and my whole team got access pretty early and quickly. Compared to the five servers we had to nurse for 2 years because that's all we'd get before then.
I personally I believe Hadoop took off at Yahoo because it was a way of getting computing resources that did not need to go through the committees. Big Data? Map Reduce? Less important than simply getting a machine to do things on even if it was just the gateway node (the game of trying gateway nodes till one wasn't at 100% cpu was always fun).