I remember that Microsoft continued with DOS for long and Windows <= 3.x (and a bit later too) was [quasi] just an UI on top of DOS.
My main explanation in 2024 is that Microsoft is Microsoft, no matter what they sell. Microsoft is a business machine like nobody have seen before, they fail at zillions of projects and acquisitions but they continue to exist and growth! Think that Apple found their way very late on so business wise Commodore was doomed, it is not about the hardware. I remember in the late 80s joking to my friends spending money on a Sound Blaster and a CGA... VGA.... SuperVGA. I developed in assembler for the 68x line and just after I learnt some x86 I couldn't believe you need to know about offsets for pointers. But Microsoft is Microsoft and Intel was Intel. The 386 line changed everything. It is documented in the Andy Groove book.
This is not personal with your comment but I think several times in HN the community doesn't understand the complexity about going to market and touching the really complex business reality. This goes far from using fancy programming languages, frameworks, etc. Even receiving huge investments.