Ugh, wall of text... I just read to the middle because I lost my motivation.
I'll just refer to the most important points.
The article is indeed quite pessimistic, yet many points are true! Microsoft did an outstanding gruesome job in marketing according to Windows RT. THIS is their platform to compete with iOS and Android. They did not even nearly enough to tell people about that platform AND didnt cooperate enough with manufacturers. The advantages of the ARM platform arent even closely maxed out. Only the Vivo Tab RT is a blast, since its a great competitor according to its light weight. RT at all failed indeed, but not because it is a bad eco system, but because MS didnt spread the word. They promoted the heck out of Windows 8, but didnt the same for RT. It was absolutely neccessary to do that, because you are bonded to the Windows Store if you purchase a WRT device.
If they studied markets and opinions of ordinary people well enough, they would have known, that the only possible way to sell a still growing eco system (which OF COURSE means it lacks apps!) is to promote the system as much as possible. They did for W8, where there wasnt any neccessarity to do so, because it sells anyway (because its Windows, duh). They should have done it with RT, but didnt. And they should have described the differences between W8 and WRT much more, to defeat the confusion.
People mostly are stupid consumption sheeps, thereby they always reduce an eco system to the app counter of its store. MS should have done much more to show them the benefits of RT.
That also includes devices. The OEMs did a horrible job either, because they have no interest to promote that platform. The RT devices are all mediocre and changeble. Like the most notebooks. None of them has a soul or created a must-have-moment at the customers. So they did their own tablet - Surface, which is definitely more edgy, outstanding and able to compete.
The fact that they made an own device REALLY upset some manufacturers - including Toshiba and especially Acer. Acer lost their sheit on Surface and bashed it (because they feared it and faced their own mediocrity, I'm damned damned shure about that...) and stopped adoption of RT.
You must create a desire in the customers. And if your product has quirks, you have to paper over the cracks with awesomeness. Microsoft left RT on its own devices, with all lacks, troubles and antipathies of people.