I see posting links to external pinball related sites as an extension of AP which benefits this site, rather than competition which erodes it.
At the end of the day, the user will ultimately close the newly opened tab back to AP after reading the link (or not click on it all if it is of no interest to them). 
I think that is the intention - there's no discussion within the links - just the story. If there were links to other forums "Hey, come over here and discuss", then I would not be pleased. What we want to encourage is discussion on these articles - so maybe posting the entire story might be the happy medium ?
