Same server BGs built rivalries. I remember folks complained about cross-realm BGs, but Blizzard added them anyway even though the “eroded” the server community.
How come Blizzard didn’t listen to folks who didn’t want Cross-Realm BGs and put them in, even though they eroded the social aspect of servers, but with Cross-Realm Dungeons (which were in the game) we’re being told “sorry, we need to preserve the social aspect of servers”.