Interesting. If it is indeed a feature rather than a bug, I think it would be only normal to also let us disable NPC damage to player-structures since we can already disable purges. This can be of all sorts of benefits for different play-modes and creative uses of Conan Exiles outside of the standard survival-playstyle, especially on private multiplayer servers.
EDIT: suggestion-topic has been opened here. This bug report can be closed/removed. Thank you. 