"Some data was illegally accessed, including a list of email addresses for global Battle.net users, outside of China. For players on North American servers (which generally includes players from North America, Latin America, Australia, New Zealand, and Southeast Asia) the answer to the personal security question, and information relating to Mobile and Dial-In Authenticators were also accessed. Based on what we curren…
This is why you never use the actual answer to that question, but actually a separate password for those.
Using a password instead of the correct answer to the question can be helpful, but in a totally different way. Specifically, it eliminates the risk that someone can guess (or research) the answer to your security questions.