If someone doesn't get to book the stay they want because the website says 5 nights in the advertising, then that is their business. We just want readers to know that it is a three-night stay and 2 day park ticket minimum for free dining, and that if they want a three or a four night stay, they can book one, assuming the resort, room category and dates they want are available at the time they try to book. It is indeed the case that you need to have a moderate resort or higher for regular dining free, but it does not have to be a 5 night stay.
I don't have enough fingers or toes to count the instances where the WDW website has been dead wrong, although in this case it's just a matter of interpreting their advertising.