First, you are ignoring a key part of history as represented by the steepness of the YC. It is at least as important as the average level. Bonds would soar (not crash) if the YC slope returned to historic norms.
This time is different
I read it, have you? Great read.
It would help you understand that a financial crisis is different with a global survey. (1800-2000's)
Have you? Tedious read but really sets the scene from 1618-1990.
It is astonishing what foolish things one can temporarily believe if one thinks too long alone ... where it is often impossible to bring one's ideas to a conclusive test either formal or experimental. J.M. Keynes