Cornerstone content is a great way to build authority increase user engagement and generate additional ideas for content on any website. Used effectively it can increase all aspects of any online business without the risk of losing any search rankings.
These pages are not sales pages there are very targeted and focused content which is what makes them very attractive in link building. However you can use cornerstone pages as landing pages to get additional information from site visitors. However my research shows that not many websites like to give a link to a landing page.