Windows as a software package would have never been affordable to individuals or local-level orgs in countries like India and Bangladesh (especially in the 2000's) that are now powerhouses of IT. Same for many SE Asian, Eastern European, African and LatinoAmerican countries as well.
Had the OS been too difficult to pirate, educators and local institutions in these countries would have certainly shifted to Linux and the like. The fact that Windows could be pirated easily is the main factor that led to its ubiquity and allowed it to become a household name. Its rapid popularity in the '00s and early '10s cemented its status as the PC operating system. It is probably the same for Microsoft Office as well (it is still a part of many schools' standard curricula).
The fact that Windows still remains pirateable to this day is perhaps intentional on Microsoft's part.
Windows being easy to pirate wasnt the reason for it's popularity. It had market share because they allowed for it to be preinstalled on machines for virtually nothing. They allowed it to be preinstalled on machines for virtually nothing because the OS wasn't the flagship product.
MS Office has always been the major flagship product for the company. This was true in 1994 and still is today. Office is so important to their revenue streams that it's fairly common knowledge and has been mentioned by former employees that OS development would focus on compatibility with Office programs, not the other way around.
Specifically if you look at the years around Office XP and 2003, that suite is used very much as a CVS. They deprecate their operating systems using Office.