A grandmother who has barely learned how to use email died in 2012.
Her friends are all in their 80s and only send 1 email a year.
Someone new registers the account and then... Then, the Holiday season in 2013 roles around and all of a sudden a new person is receiving emails from another person's friends.
At that point, the scams they could pull off would be insanely easy.
Additionally: Any sensitive material intended for the original person would instantly be compromised.
Yahoo is playing a somewhat dangerous game. The better option would have been to buy a domain name similar to Yahoo.com and use that.
[ADDED] Now I'm really mad. I tried logging in and it requires me to send an email to an account I had when I signed up for yahoo 10 years ago to log in because it "doesn't recognize my device". Just like Google there is no way to email them or contact them. Unacceptable. There is no way for me to log in to my account.