So I have come down off of my high horse and realize that Hammond actually has a point when talking about the Macedonian aristocracy as though it did not exist, just that it did exist. The following is now a piece of my thesis, but could be an entire book/thesis/article on its own and may seem odd, so bear with me.
Philip II caused the creation of the Hellenistic kingdoms. Alexander’s father died in 336 BCE, Alexander followed in 323, and when Alexander’s heirs finally died in 305, members of the Macedonian Aristocracy took the title of basileus (king). Even then, the final shape of the kingdoms was not established until around 280 BCE when Seleukos Nikator defeated Lysimachos, which allowed Demetrios Poliorketes (then Antigonos Gonatos) retake Macedonia. So the real question is how did Philip, who had died 31 years before the coronation and 56 years before the final shape of the kingdoms was established cause their creation?
Prior to Philip the aristocracy was quite independent, especially in Upper Macedonia, but they never seriously threatened the king beyond an occasional assassination because the Argead family had so much more power. The king controlled a monopoly on all metal mines (gold, silver, iron, tin, copper, etc), as well as timber resources. With these resources firmly in his grasp, the king was the state, plain and simple. Further, the king was the military commander at every battle and there was an instance of an infant king arriving at the battlefield for no other reason than that the the king had to be there.
The Macedonia Philip inherited (or stole from his nephew, however you want to read that), was weak, surrounded by enemies and not in control of all its own territory. Early in his reign Philip won victories militarily, but also diplomatically and financially (one of his most famous sayings was that no fortress is impregnable if he could get a donkey cart full of gold into it). Previously the kingdom had been small enough that the king was able to command every military venture, but as Philip expanded it and campaigned elsewhere, he was no longer able to lead all of the soldiers. Gradually more and more aristocrats rose to command segments of the army. Alexander continued this trend since he campaigned even further afield than did Philip, and had to leave troops behind to protect areas, such as half of the available military remained in Macedonia with Antipatros.
Another of Philip’s policies that strengthened the aristocracy was that as the kingdom expanded, he also increased the number of aristocrats and strengthened the ones already in existence by giving out land grants in the conquered territories, and incorporating the Upper Macedonian noble families. While Philip kept the usual monopolies of the Macedonian aristocracy, expanding land grants meant that other families grew in strength vis a vis the Argead dynasty. Alexander then took a massive leap by giving away all land owned by the king in Macedonia in favor of whatever he could take in Asia, though he probably kept the mines and timber monopolies intact. Then in Asia land, treasure and honor was given to various aristocrats in the same way that Philip had distributed such prizes.
Finally in 305 the token fealty given to Alexander IV evaporated and the young man was killed. Afterwards the aristocracy took the provinces that they ruled and declared themselves kings over that territory. The obvious answer is that Alexander caused this divide by not providing an heir before leaving on campaign–if he had, the young man would have been around 12 when Alexander died and may have been old enough to grow into the kingship while loyalty to Alexander still existed, considering that it took nearly 18 years without a proper heir.
My contention, however, is that Philip caused the eventual creation of the Hellenistic kingdoms because he strengthened the aristocracy. Even for a 12 year old things could have easily degenerated into the same situation because there was no other Argead and the Macedonian aristocracy was so strong. Going down a contrafactual thread, even if the Hellenistic kingdoms didn’t immediately emerge, the moment the Argead king suffered military setbacks the aristocracy could have killed him, or the first heir could have done well, but would have needed the aristocracy that they would have grown increasingly in strength until they removed the king in a generation or two.
Partly this is the nature of the Persian state Alexander transformed Macedonia into because the empire was so expansive that aristocrats had virtual autonomy in most places, but Alexander also tried to incorporate Persians who were used to the system. Philip started the trend of empowering the nobility and with so much of what he did, Alexander was not so much innovating as continuing the policies of Philip.