K.A. Rutledge

You are detecting the difference between the verbatim elements common in nature and the way artistry can communicate with seemingly unnatural affectation.

Actually, there are a lot of species (large trees in nature) that do have their secondary and tertiarty branching growing up from the primary branch. I just walked out of my front door and saw 3 examples. So, your generalization doesn't work in the overall. However, neither is it "the" way to create bonsai foliage pads by having the shoots standing on the primary branch. Many bonsai branch forms have the secondary and tertiary shoots moving down from the primary branch. This form does, however, generally require some foliage above the primary branch so that it does not look awkward.

In the end, there are many ways to make good looking bonsai branches; some by replcating what nature commonly shows us and some by using artistic affectation to evoke a natural look-and-feel.

Kind regards,
Andy Rutledge
zone 8, Texas