It is, however, an exception to the rule.
Computer industry is littered with bodies of slain giants: Borland, Sybase, Lotus, Wordstar, Personal Software (VisiCalc) etc. The rest are companies that stabilized into a success (Oracle, eBay, Microsoft).
It's exceedingly rare to make a come back (IBM, Apple are 2 examples I can think of).
IBM was never any good at B2C. Getting back to B2B played to it's strengths.
Microsoft didn't invent the Kinect, it was developed by PrimeSense and brought to market by Microsoft (if I've got that right).
As the cost of much of the large technology plays comes down, and it can be done easier, I think we'll continue to see large companies continue to rely on start-ups to provide the initial impetus of ingenuity. I suspect it has always been that way. Don't forget Microsoft was a start-up which took advantage of IBM's scale to build their market advantage.
The skeletal tracking was totally Microsoft's stuff; in fact, it was an utter surprise to PrimeSense when it was announced (that was fun -- they had no idea what we were really doing with the camera until very late in the game).
So: PrimeSense: Depth camera.
Microsoft: EVERYTHING else (from the firmware and the drivers on up, including a /bunch/ of manufacturability stuff that PS had little experience in).