Microsoft did not bring the personal computer into every home for a reasonable price. Apple didn't either: the II was quite expensive when compared to the Commodores and Ataris and was more a "low-end professional computer". If someone could be credited by bringing the personal computer into the home with reasonable prices, Commodore should get that honor.

If DOS weren't so popular as to turn the the PC platform into a commodity, other platform would certainly become dominant. If not, an OS like Unix, that could bridge the gap between different platforms, would emerge as the OS of choice to develop for. Microsoft tried to position itself that way with Xenix but, ultimately, saw the PC clones and DOS as viable options to take that role. They tried the same move with MSX with a much more limited success (primarily because of the PC price drop).

If Microsoft could be credited for something, it should be of limiting the diversity in the PC scene. While in the late 70s and early 80s you had at least half a dozen different platforms with different software and characteristics, today you have only one with different performance and price points. No one is crazy enough to innovate out of Windows compatibility.