WordPress.com, undeletable accounts

I discovered a website recently called JustDelete.me that serves as a way to help people delete troublesome online accounts that make it hard to delete them. WordPress.com is one of the worst offenders; it doesn't allow accounts to be deleted at all. To be fair, it does allow people to delete “identifying data” associated with an account, but not delete the account itself. JustDelete.me also points to WordPress.com's relevant accounts page that offers more information. I've never tried to delete my WordPress.com account, so this is news to me. I wonder why they can't be deleted.