It’s not only that string references are bad, but tag usage must also be used with caution because if you have multiple GameObjects with the same tag, it does not guarantee which one will be returned, that’s why it’s mostly used to find UNIQUE objects in the scene.
Of course the best way to get a hold of an object, is by just assigning it in the inspector, that’s the least expensive and also the safest method to do your job, however, in this case it doesn’t matter if we use tags, we want to find a UNIQUE object in the scene and we know that there won’t be another object with the “Player” tag.
It also doesn’t matter if you’re in a basic, advanced, expert course, the goal here (and I think it was already said many times prior to reaching the Enemy AI section), is to first get something to work with, then refactor along the way. Sam chose to do it this way, someone else might use inspector assignment from the beginning, you are always welcome to improve anything you are given in this course.