I would put aside statistics and whether we completely understand how the economy works (we don't).

Just ask...are there are very fundamental differences between the finances of an individual and the government? There are. For starters, the government can simply print money and pay off debts. They can also choose, by their actions, to inflate away nominal liabilities.

So then it is reasonable to consider that "being in debt" may have different ramifications for the government than for an individual.