It includes a point similar to one made by madtripper - that we automatically use familiar objects (an example would be a bench seat) of known size to help us judge ('scale') the size of their surroundings, whereas the size of plants and rocks is so variable that we don't automatically use them in that way.

A recommendation in the article that seems to me to be especially valuable is that in home gardens the aim should not be not to make a Japanese style garden feel larger, but to make it feel closer. Intimacy, it says, is more desirable in such a garden than grandeur. I think I agree. Do you?