Over the past few decades the global financial system has steadily become completely unrecognizable from the standpoint of classical economics. Debt is not debt, savings is not savings, and printing money is no big deal (or so they say).
The global repo market is valued at $12T USD, and only 75% of it is backed by "pristine collateral", such as government bonds. That means that $3T of it is in equities or derivatives. The fed's balance sheet is only $4T USD in comparison. Additionally, $.5T is in private capital groups, which are entirely opaque, have poor lending standards, and there's no visibility into counterparties or volume.
Keep in mind, India's Yes bank that was just nationalized failed due to liquidity problems. There is a theory that global liquidity is being challenged, and central banks may not have the appetite to provide a backstop at the volume required.