What a bunch of badly behaved "services"! It is not that hard to roundtrip an email. It's a service to the _actual_ user, who doesn't lose control of the account when the actual email account holder notifies the service, hey, that ain't me. It's a service to the rest of us, who don't actually use your service -- and who one day _might_ and then find themselves unable to access their account.
In this case, the person had never done anything with the account. Disqus is cheeky, they "recommend" you don't delete the account so that no one else will post using your email. _Because they let anyone post using any email_.
If you have ever encountered disqus as a service, I cannot imagine what they are providing of benefit to anyone, but with controls this nonexistent, I'd have to say don't bother. If someone thinks I'm being unfair, I'd be interested in hearing the rationale for the service and the laxity of enforcement on emails associated with accounts. This isn't like Redbox or Macy's or Toys R Us or a bunch of shops in the UK that just accept emails and blast out IRL receipts to them, where the roundtrip would be time consuming and not really worth it.
Firstname.Lastname on gmail provides me with an unending stream of entertainment and information on what companies are so ridiculous I should avoid them.
ETA: I wonder if they are suggesting people keep accounts other people created with their email as a way of inflating their numbers. Or, more cynically, harvesting reused passwords for hacking.