My statement is rather specific and most certainly true. I have died many times because npcs sit inside of a wall casting on me and I am unable to get to them and kill them. Pretty easy to discern what the problem is. I have even had melee only npcs go under the world and start tearing me a new one. Luckily that is easier to fix because they tend to chase you closely. Casters, however, do not.
There are no specific instances, as it has happened in nearly every dungeon I have been to. Only recently have I begun dying, but that is because npcs are nuking much harder than at lower levels. I understand pathing is something that will not be implemented, but I don't think LOS should be disregarded.