WoD still had HFC, at best the final raid would have taken place partially in Azeroth.
Legion had us on Argus, but again could have sent us back to Azeroth instead of the Seat of the Pantheon, we quite literally see Azeroth from the final boss room.
BfA is a fair example for sure, but even then there were many, me included, that didnt really think Blizzard was actually going to have such a drastic shift from Faction war to Old gods.
For this expansion however we do not have any obvious candidates for final raid, especially seeing as we are already going to Torghast for a raid, and it would just be silly to go there again for another final climactic battle.
On a greater level though. Of course people will speculate that the final raid will take us to Azeroth or some well known place like Stormwind. People generally like callbacks, and the concept of coming full circle in a story is on of the most tried and tested concepts we have. Why wouldnt it be a good idea for the finale of a faction war story dealing with death if Sylvanas attacked Stormwind intending to kill and raise the inhabitants?