Re: "the company's audacious early goal of putting a PC into every home came to fruition"
Amiga was never "niche", except later in its life when the PC got the 3DFX card to go with the Soundblaster Pro and 16. If you were as old as me, you'd know that the Amiga was the shit back in its day. Microsoft operating systems were still a whole bunch of 640k limits and creating custom config.sys and autoexec.bat files to make stuff work properly.
What MS got that many people failed to get is having a half-decent office suite, but it would only run on their half-baked OS. MS did nothing, precisely nada to lower the prices of PCs. Amstrad did more than they ever would, with a "pile it high, sell it cheap" mentality that might not have resulted in the best hardware, but resulted in "good enough" to run Microsoft's incredibly expensive office software along with the operating system seemingly designed from the start to lock everyone into it.
You might laugh, but Linux and the Penguinistas have done more to make PCs affordable than Microsoft ever have. Yes, really. Microsoft can't get away with charging more than the cost of the hardware on an office suite any more, when products such as OO.o and LO.o are "good enough", and free. The Microsoftians know this as well, hence their total war against free with proxy companies, groups, and unproven patent allegations.
I will state again that the only role Microsoft has ever played is to demand a toll to cross a bridge made of everybody else's hard work.