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.
Linux’s development would have accelerated a lot had there been more demand. There wasn’t enough demand because pirated Windows was getting the work done.
In the 90s there where a lot more OS available to compete agains windows, who already had existing software (sometimes better and more capable) to compete with windows: MacOS (Popular in print, layout), BeOS, OS2/warp (tried to replace windows), Amiga OS (best for video editing work at the time), Atari, Novell Netware.
It’s not exactly like people where desperate for another OS at this point in the late 90s/early 2000s.
I don’t think that necessarily holds true for OSS. The average user with no development experience wanting to use an open source project doesn’t mean it will always develop faster.