And next you know, Nikon - as Canon has done before many times - clandestinely changes their lens mount protocol [starting with D5300], so Sigma lenses stop functioning properly on that camera, but not Nikon lenses.
You may call it a mere coincidence. I call it ... just another tree in the huge forest of anti-competitive behaviour, collusion and market manipulation.
At last, one point I can partially agree with. (Out of a whole forest, BTW)
I do think it is poor business policy and poor customer service for companies to purposely disable third party accessories. (Unless, of course, those components could potentially damage the product).
As many know, I've long complained that when Canon introduced the 600 RT, they refused to offer a receiver that would allow their own product, the 580EXII to function on radio control. In my view it was shortsighted and contemptuous of their customers, since they could easily produce a receiver or transceiver for probably less than $50 and charge users $200 or more for it. (I base those prices on the excellent Yongnuo 622 transceiver.)
More to the point though is the case of Canon crippling the 5DIII so that it cannot function using the Yongnuo ST-E2, but can use the Canon ST-E2. That was a clearly anti-competitive action on their part and is particularly frustrating because the Yongnuo product is so superior to the Canon (three flash groups instead of two, greater range, rotating head).
The irony, though, is that when companies stoop to these types of behavior, it usually backfires on them. They punish their customers, while the competitor simply works overtime to improve their products. I'm sure Canon's actions provided an incentive for Yongnuo to offer the 622 and to now develop a 600-RT competitor.
Similarly, there is no doubt that Sigma produced its lens dock precisely so that they can thwart attempts by Nikon and Canon to change lens protocols. Additionally, I believe Sigma's new policy of offering lens mount conversions will further discourage this practice.
So, while I share Mr. Aperture Value Time Value Manual's frustration with these anti-competitive behaviors, I note that they are seldom successful for very long. These kinds of bad behavior tend to also be bad business decisions in the long run – they feed into customer dissatisfaction at the same time they spur innovation among competitors – two things that the companies should not be encouraging.