battle.net added the ability to install different versions ala Steam (well, okay, to more clearly have the ability to do this it was buried in some menus for Overwatch betas), I wonder if they might be changing this to only install WarZone/MW, they have to know about the storage space complaints
ironically, CoD used to always come as split SP/MP installs until Blops III dropped it (WWII briefly brought it back) but they always let you uninstall the campaigns on Steam (even if it saved you no space on some of the games since they were just different exe's and scripts), I figured Blops IIII it was just an oversight due to it all being technically multiplayer, was kinda surprised when this game was the same way