It will be useful in case project is configured with DDM template and one should not be allowed to add participants manually.
With this feature, Business will get benefits in terms of avoiding project delay as incorrect recipients' addition error (by Manal effort) will no longer happen.
This can be introduced to system the same way it is introduced for "Package Types" required field - Check boxes for Mandatory/Non-Mandatory.
In case of a large project ecosystem, we should have the possibility to centralize all the Distribution lists so the master project can push his own distribution list to the statellite project. Those push distribution list should be read only by default and modify only from the orignator.
However for Tiers 1 partner, provide the option to transfert the rights to edit. Usually tiers one haveethe ressources and the expertise and are deeply integrate into the main organization that own the project.