[zamnos]

2^32 is 4294967296, or 4 GiB. Back before Windows ran on 64-bit machines, 4 GiB was as big a number as a standard int could represent. Updating it for 64-bit mode would mean breaking 32-bit programs, so "fixing" it isn't necessarily an upgrade.

[Twirrim]

I think OP was suggesting that instead of overflowing, the API could have instead returned 2^32 / 4 GiB.