This post draws its data from the aggregated logs of tens of thousands of sites hosted on Acquia Cloud which are managed and analyzed by our internal log analysis tool.
In Drupal 7, definition and altering of blocks are done through block specific mechanisms. A block was defined by implementing providing the available deltas and the corresponding administrative labels
This allows you to use all the Drupal 8 features to edit your content but present the content not only on a Drupal frontend but also on mobile apps or anything else that can work with JSON data.
This means that if you have a 5-year-old Drupal 6 site, you will find major value in upgrading directly to Drupal 8. Many other benefits can justify the cost, including an easier to administer, responsive site.