I wonder that too lol!
I haven't publicized it much though, maybe in around three threads when it could help the OP.
Perhaps everybody has Task Manager running in a second monitor lol, I don't know. But even if they do it's very useful to have all the info available in the same place. You can see the bottlenecks happening in real time while you game and start making sense of when and why your fps drops.
For example, in Crysis I hit a CPU bottleneck on the first two cores when there are too many enemies in the vicinity (A.I. intensive), it's interesting to start establishing patterns and understand the game engine's limitations.