You don't know Microsoft very well, then. They've literally never done anything else!
1) They were late to the party with DOS. They ripped off QDOS and sold it to IBM. It was IBM who launched Microsoft, it was Microsoft's non-exclusive contract with IBM that allowed the IBM compatible market to begin. That had never been done before, and only happened because IBM didn't take the microcomputer seriously.
2) They were late to the party for GUI. Windows was quickly thrown together after trying to work together with IBM and deciding to be dicks to IBM and steal lots of their design work.
3) Windows '95 was a rebrand of "Windows". So was Windows CE ME NT, XP, Vista, Mobile, and RT. In a sense, Windows 7 is the first "debranding" of Windows back to its marketing roots.
4) Microsoft goes through a major change in structure every 2-5 years. It's always made the tech rags, all the way back to the 1980s.
5) Their now dominant office was a rebrand of their MS Word, Excel, and Power Point, which were sold separately.
6) Each of these Office products was a late comer in its field, in part winning due to strange incompatibilities encountered by the "other guys". Remember the phrase "DOS isn't done until Lotus won't run". Lotus 123 was the leading spreadsheet at the time.
and so on.... Just don't pretend that this BS is anything *new*. Market conditions were right, and MS had a combination of luck and determination to make the best of it. The market conditions have changed remarkably.