This is them bouncing back to Legion style of storytelling where every player does every zone.
They clearly see Alliance players playing the Alliance content and ignoring the Horde content as well as Horde players playing the Horde content and ignoring the Alliance content as one of the core issues with the players receiving BFA badly.
They tried an achievement with mount rewards in BFA to counter this. I assume it didn’t work to their satisfaction cause now they are simply removing the choice to ignore the other faction’s content.
The bungling of the Night Elf narrative continues.
It isn’t like this was hard to foresee.