Fair enough, though it's still not a hardware reason.

You could have just given 16bit handles to all 32bit programs, with the con being harder 64<->32 interoperability (since sending a handle from 64 to 32/16 would require faking it), but then you would not break _existing_ applications at least. Guessing 32bit handles also broke quite some 32 bit applications.

In retrospective, I would not have made it the way I describe either way, since it looks like people could care less about old 16-bit compatibility, and on the other hand 32<->64 coexistence was common for quite a while.