When any end user can easily add the functionality you are referring to, for free, to an operating system you can buy, pre-installed on a 7" tablet with an SSD, Quadcore x86 CPU and HDMI out, for less than £70... I think you might be making a flawed comparison.

How exactly does one freely and easily add (reasonably expected) functionality to OS X? Due to how much escalation was required, even Apple themselves thought it should work.

As the article stated, you can make the hardware do what you want to by changing the software (OS X to Windows or Linux); in other words, the hardware isn't the limitation, only the software. In my example, your computer's hardware is fully capable of being used for SSH, you just have to use the right software.

My point being, unless Apple sabotaged the hardware to make it only usable with their brand of displays, there's really no harm done here. You don't buy a 4K TV, hook it up to a 2005 era DVD player, and expect to see 4K resolution on the screen just because your TV had a plug that accepted the DVD player's cable. Just because the plug fits doesn't mean the capability is there. If you want MST over DP, use the software that allows for it, and if that means installing another OS, then so be it. Petition Apple to allow MST over DP as well as Thunderbolt and explain to them that they lost a Mac user to Windows or Linux because of this.

I hope that makes it easier to understand.