Graphite Shafts in Titleist Drivers

Why do custom club builders insist that the graphite shafts in Titleist and other brand name drivers are counterfeit? I have read on several websites and also viewed a video on Youtube that says the shafts aren't the true aftermarket shafts that their labeling implies. I purchased a new Titleist 910D2 driver with a Mitsubishi Diamana Ka'ili shaft in it. One of the reasons I was willing to pay $400 is because of the cost of that shaft. One thing I find disturbing is that Mitsubishi claims on their website that their shafts are manufactured in Japan and the label on my new driver says that the head and shaft were manufactured in China, so what gives here? Thanks.

They are not fake they are just "made for". The 910 diamana shafts are not original but in the 913 they are all the oem aftermarket shafts.

The stock shafts in the 910 drivers were actually aftermarket shafts so that is why they were made in China.  I believe the new shafts in the 913 are actually the real shafts.