[schmuckonwheels]

> windows 2000 wasn't widely used as a consumer installed OS

But Windows XP, which came out in 2001, inherited everything from Windows 2000 and more, and was used extensively for gaming.

[Sleaker]

Absolutely and first iterations of steam hardware survey showed mostly XP users, but still 5-7% win 98 install base, which they maintained compatibility with for quite a while, that's just to say that I can see why they might not have used those specific windows APIs at the start.