It's not about linking, it's about re-posting titles and excerpts of news, like Google News does (did?)

A few days of Google-FB-Twitter blackout for Spain would reverse this law, but the newspapers that proposed it should be banned forever from the search engines and social sites, to teach them a lesson.

The Heise article says that a mere link to the URL is enough (https://news.ycombinator.com/item?id=8091162). I really hope they mistook some Spanish source.

and the point is that these publishers don't realize that all these news aggregators are sending a considerable amount of visits to them this is a picture of an editorial celebrating that this law was passed and how they include the buttons to send the article to the aggregators: http://mnmstatic.net/cache/21/eb/thumb_medium-2223027.jpg

There's no hypocrisy there. The law appears to be based on the idea that sending the article on social media should produce money for the article writer... obviously this would be a reason to encourage flowing the article out to social media rather than inhibiting it.