Small rock garden landscaping ideas like this one can make good use of out of the way, distant, or otherwise unusable areas. And in a case like this one, can make a very unique focal point.
The white rocks in this garden are visible from a great distance and naturally draw attention to themselves. White is a natural attention getter and is often used in landscaping and other art forms to create focal points.
You can create different effects in a rock garden by either placing the rocks on top of the ground or by placing them slightly in the ground. It mostly depends on the effect you're trying to create.
Often, miniature rock landscaping ideas are an artistic replication of Alpine landscapes. So it all depends on what the artist that's creating the garden sees.
Since Alpine and rock gardens are intended to be a small miniature version of rock Alpine landscapes, miniature versions of plants are often used.