Using classic Outlook for Windows in business environments
As a former programmer I can guess how this happened - MS outsourced the email system to another country, different cultures have a different way of looking at things. What they see as logical may not be for an American.
MS gave the contractor an email modification project, the contractor completed it, MS signed off on it and it went into production. The contractor's staff went onto their next project and there was no facility to go back and make changes. So no one at MS cared to read the responses.
Just a guess, but we know companies outsource offshore to save money and the customer sucks it up.