Even this isn’t a solution since people paid for accounts in OW1. They can’t just ban them or block access now. Sure, they can stop the creation of new accounts but that does nothing to stop the players with 10+ accounts.
Then add on the likely annual rank resets…That applies to smurfs as well. It’s a free smurf account every year. For every account.
I don’t see how Blizzard can fix that.