You know that account you set up 6 years ago and used only as a verification email for a site you almost never go to? Won't you be surprised next time you need to reset your password.
I mean, at some point, you use the account or you don't. I think they are trying to clean up those throw away emails and ones that have been abandoned.
You will be notified on the backup email address you had the option of providing. If you didn't set one up you're probably not going to get a notification.