Because you pay 15$ a month and 50$ every two years for continuity errors.
No, I can fault them for not knowing the game they are working on. I could care less if they are the original development team or not, if they give a shit about their paycheck or the game they'd know more about it than the fans.
It's their job. It's literally the only thing you and I or anyone pays them to do: Deliver a quality product for the money we throw at them.
Giving Blizzard the benefit of the doubt over literally anything at this point, especially when its a product and not a service, is exactly why a game and a development team this low effort can stay in the "best mmo" category for a decade. Learn how2consume.