Let me try to explain this a little better
What came first? The little trees in pots, or art? I'm thinking the art came first, probably back the the Egyptian or Sumerian cultures. Around 5000 to 6000 years ago. They had carvings, sculptures even paintings way back then. Sure we call bonsai art but I think this is a recent event. I doubt you would find anyone 500 years ago saying that bonsai is art.
{Let the tree tell you what it want's to be.}
We all do this every time we evaluate a tree for bonsai possibilities. Start from the soil up. does it have good nebari or roots that can become good nebari with a little work? Are the roots level with the base of the tree? Does it have a straight trunk with taper? Does it have taper up the trunk and branhes in the right place? That type of tree could become a nice broom style.
Is the trunk planted at an angle? Does it have taper in the first few inches and good nebari? If so it could make a nice informal upright or slanting style or even other possibilites.
Does the tree have lousy nebari, inverse taper and no chance of becoming a good bonsai? This is the kind that is telling you to put it in the compost pile. Why would you want to waste your time with something like that?
Like I said. Let the tree tell you what it wants to become. Maybe better put, what it has the possibility to become.
Tony