Somewhere in the docs they state that they must also recreate whatever bugs the API has, otherwise applications written with those bugs as an (implicit) assumption could misbehave.
its worse than that, Windows activates/deactivates "bugs" based on the compatibility profile of the app.
so you can set an app to use a Windows XP compatibility profile, and this will simulate Windows bugs which were fixed in more recent versions of the OS
so you can set an app to use a Windows XP compatibility profile, and this will simulate Windows bugs which were fixed in more recent versions of the OS