It really does look like Apple specifically has disabled it because there isn't an apple product that supports it, but that may be due to my own ignorance of MST.
Should I blame Microsoft for not supplying all software ever written with Windows? After all, my PC is just a Turing machine, so by not providing me with all the software ever written, they're locking out functionality the underlying hardware supports.
Consider that an Operating System is just a simulation of a nicer Turing Machine than the hard-wired Turing Machine on which it runs. Similarly, an “interpreter” is just a nicer Turing Machine that is being simulated on top of an OS.
So, for a complete analogy, we’d need a company that either restricts what kind of OS that you can run on the hardware that they sold you, or that restricts what kind of interpreters you can run on the OS that they licensed you.
The confusion lies in the fact that Apple does support Thunderbolt monitor daisy chaining, and Thunderbolt uses the same port as mini-DisplayPort.
That the hardware can support it is irrelevant. Apple hardware can do lots of things that Apple doesn't support or claim their hardware can do.
Call it malevance on Apple's part if you want, but it's really just them choosing to only support some things, not all the things.