That's kind of what I'm getting at with the first part of my post. Doomsday for the Fed is "major collapse of sector(s) the US economy they fail to arrest" or esoteric economic woe that requires drastic but relatively novel (legally speaking) measures to address. The kind of systemic seizing that some of the people who had the foresight and money to have made a killing on 2008 but didn't because they feared the wholesale collapse would happen because they didn't factor in the firehose of money that would be directed at the problem.

Complete societal collapse is outside their purview because they depend on there to be an economy to manage which ceases to meaningfully exist at certain points on the Doomsday scale.