Iphone vs Mac Mail app

I did the yahoo transition for my mom's account and it was very  simple on the iPhone.  But why is it that we have to do a 25 step transition put together by some very thoughtful and helpful members here?  Is it because cox or yahoo didn't dedicate enough resources to Mac Mail?  I'm just trying to understand this part of it.  It used to be that you'd just add the email, password, imap address etc, and all would be well.