In patch 8.1, the reputation faction Champions of Azeroth in Battle for Azeroth will be account-wide.
Champions of Azeroth is one of the important reputation factions in BFA regarding boosting up your ilvl of your Heart of Azeroth necklace.
When you reach friendly, honored and revered, you head to Magni in Silithus to get 16 more item levels in your Heart of Azerith.
This was frustrating when you have alts or a new main because you had to grind reputation all over again. But not anymore when patch 8.1 is out.