I can see you're determined to be "right" here and aren't interested in the reason systems are implemented that way. So I'll drop it here and let you "win".
I'm tempted to inform you about DDOS attacks and how allowing all your users to get locked out due to a determined and persistent threat is probably a worse user experience than not having a "Your password is expired, please change it" message, but no, you're totally right, and somehow I just couldn't see your brilliant solution to all the problems I mentioned and was determined to naysay you. My bad.
We could just concede every time to the user experience guys, and hey, we probably should, life's a lot more fun when you ignore security best practices.