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So the bitcoin ledger is a debt "the public bitcoin system" owes to each "creditor" (bitcoin holders). It's a pretty good analogy except the tally sticks were not limited in supply.
No, that's not a very good analogy. For the concept of debtor and creditor to make sense, the bitcoin system would have to be an entity that is capable of making a decision to withold the credit or re-sell the debt. It also implies a contract between the system and the users to allow access to them and only them, which is not the case.
You have 3 objections which I refute:
1) When a new buyer is deciding not to buy more coin, he's withholding credit.
2) When an owner sells the coin, he's re-selling the debt.
3) The coin pieces are unique to each holder of their half of the bitcoin tally-debt. The ledger is the other half.
Granted the ledger is not the recipient of the credit, but other previous bitcoin holders are. By "bitcoin system" being the debtor I am being liberal in including the entire "ecosystem". We can make definitions so strict that nothing in the world is like a tally system, but the point is to try to place various concepts in an hierarchy of understanding so that we can process things more efficiently.