credit for what? what message, exactly?
players will only ever have a notification if they participated. it does not matter if they log off before the raid is completed. it only matters how long they were offline. by default that is 20 minutes (Lock Treasure Max Inactive Time (Minutes)) before they do not receive anything.
it is not fair that someone disconnects and doesn't receive anything for their efforts especially when their client may have crashed, or they had to suddenly leave
this of course does not apply if they die and disconnect or die while disconnected as the game destroys their player entity at that point