Sorry to put it that way. But…
Yeah the A.I. on this monster is just so immersion breaking. It makes you realize your playing a game with an area that couldn’t be bothered to be set up well, and takes away from resourceful players. If you careful move into a position, and ready ambush the spider, you can watch it, before you even attack, or give away the element of surprise, move to a spot where it cannot be attacked, it also abandons it’s roaming movement path to stay in that location.
To the programmer who did this, it is not a quality solution to the problem of players exploiting a way to get an easy kill on the spider. This forces a fight head on against it, making for a grindy heal and hit race. When monster A.I. has them doing things like this, it destroys immersion and sense of reward for tactically trying to fight them. It places the game experience on railroad tracks, which is a detriment for a sandbox survival game. More than one way, even ways the developer couldn’t have predicted, should be allowed, and if needed tweaked.
Changing it to where the spider can damage, destroy, the tree you are in, be awesome. Remove the rocks, alright. But having it just by A.I. program flow fiat be impossible to fight any other way than head on? No, it loses the plot on the genre and play style this game claims to be.