Why would somebody want to pick up a physical box with a digital game code inside of it in 2018? It’s hard to say, really. But for those players, at least the ones in Europe, they can go ahead and pre-purchase World of Warcraft: Battle for Azeroth from select retailers.
Blizzard is making the pre-purchase for the expansion available in stores and stresses that this does not contain a physical disc (just in case you were trying to head off downloading bandwith or something). Instead, each box holds a code that can be applied to an account that will secure it for the expansion and allow immediate access to a level 110 character boost.
The pre-purchase page lists all of the retailers in their various countries, so if you’re on the prowl for a copy and don’t (or can’t) buy it through the Blizzard online store itself, this is the best way to find the nearest outlet that is selling these.