From https://gitter.im/solid/data-interoperability-panel?at=6138b630f3449e13a4608150:

I believe that was related to cases where (for example) I grant you access to project 5, with inherited access to project 5’s tasks, and then i add a new task to project 5. you should automatically have access to that new task
so i think this was meant to capture the need for the authz system to authorize by relationship