The "subscriber link" mechanism allows an LWN.net subscriber to generate a
special URL for a subscription-only article. That URL can then be given to
others, who will be able to access the article regardless of whether they
are subscribed. This feature is made available as a service to LWN
subscribers, and in the hope that they will use it to spread the word about
their favorite LWN articles.
If this feature is abused, it will hurt LWN's subscription revenues and
defeat the whole point. Subscriber links may go away if that comes about.