rock damage isn't attributed to any player. it's "environmental" for lack of a better word.
as you know, multiple players can each attack the same creature. when said creature dies and players loot, whatever loot the creature had is split amongst the players automatically when they view its corpse. ever killed a barracoon? you get maybe 5-10 items when you view the corpse. but 2 min later, the corpse "goes public" and you see 50 items.
well i noticed when i did navery solo that there wouldn't be much on its corpse. i had to wait for it to go public to see the rest. that told me some of the loot was being hidden because the damage being done by the rocks wasn't attributed to me.
first, i don't know if receiving an item from navery (as I have never got one) is based on the RNG, or if it's based on the amount of damage, if it must be looted, or if it appears in your pack.
if it is not RNG driven and doing more damage gives a better chance then someone running around doing rocks is doing environmental damage and not adding to their total damage done to navery.