If you have a Blizzard account and want to cancel your account, you can do that here: https://us.battle.net/support/en/article/2659
replies(2):
The last step for me to stop doing business with a bad actor is by giving up my privacy.
I guarantee 100% that this is the exact reason. If they're truly deleting ALL your data, could you imagine the customer service nightmare if someone's account got hacked and the attacker could issue a request to delete the entire account with no method for recovery?
Blizzard obviously doesn't authenticate these IDs as that isn't really possible.
The fact that you can do essentially anything to a Battle.net account with just an ID scan is a huge vulnerability.