Why do people keep saying this? (referring to the "low" fps)
Because the flagship sorts cameras are coming out at 14fps. When you see 4 vs 14, people think that they must be really missing something. They might not expect the top end, but they are expecting close to it.
Obviously, this high FPS expectation from a camera with more resolution than any other "full frame" digital camera ever made is ridiculous.
Honestly, when I shot at the PGA this year, even 14fps would not have helped me get any more keepers. I was using the D300 with grip, I think that is like 7fps. I think that I would have been the same with 4 fps too. Timing is more important. And honestly, the racket that the shutters make at golf tournaments is just insane nowadays going at those speeds. I managed to snap these with my lowly D300.