Linked reports is a great feature and helps in easy maintenance. You can easily avoid any duplicity of the report just for the sake of security. For example if a report has got 5 regions like Europ, NA, Asia, China, SA. You don’t need 5 different versions of report and instead you can have one single report with report parameters pointing to region and easily grant access to relevant AD groups to access their own regional reports. Any single change made in the main RDL file will immediately reflect in other regions as well and no need to make the same change in each regions. Imagine if you have 50 departments and if you are in this situation, linked reports concept a real handy one.
A quick demo is available here.