There is a use-case that requires target binding between two component properties.
I have Hybrid-2 design which allows end-users to select resource provider when subscribing. The provisioned application (AOS in this case) requires an Application Server (Tomcat) and DB (Postgres). The end-user can select in which provider the AS and DB should get provisioned. In the picture, there can be either Azure or AWS selected and the leaf nodes will provision one pair (using the Clone Pattern in the leaf node parents, only one AS and one DB is provisioned). Once the infrastructure (AS/DB) is provisioned, the AOS component (deploying application war files into AS and creating DB schema in DB) is provisioned. For AOS to work correctly, it needs to know the AS IP address and DB IP address. As the AS/DB can be one of the many leaf nodes, there can't be direct source binding between AOS AS IP Address property and multiple AS IP address properties (nor between AOS DB IP Address property and multiple DB IP address properties). Instead, it would be great to have target binding which would propagate the value from AS/DB nodes to the AOS component.