Likely this is to protect against hacked accounts and the hackers deleting the account after trading away WoW items or whatnot. I've had an off/on idle WoW/Bliz

Likely this is to protect against hacked accounts and the hackers deleting the account after trading away WoW items or whatnot. I've had an off/on idle WoW/Blizzard account for 10 or so years now, most folks don't want to delete their accounts when they don't play, they just let their subscription expire, so this seems like the most likely reason this is in place.