[rmah]

Letting the yields go up means that it becomes more difficult for companies to borrow money during a period of economic stress. This would mean those companies are at greater financial risk. Which is the exact opposite of the Fed's goal.

[rlucas]

Put another way, in an information-theoretic view of markets and money: stopping the yields from going up would make it more difficult for investors reliably to gauge how safe it is to lend money during a time of economic stress.

It's also not a scaling function (reduce everyone's cost of borrowing by 10%, say). There's a floor so you get a clipping effect.

The Fed's intervention is like the CD mastering Loudness Wars.

[mindslight]

Not more "difficult" - more expensive. A possibility that every company should have foreseen with financial modeling, and so avoided taking on more debt than they could handle during a recession.