The government ran up $8 trillion in debt prior to 2008 with no help from the FED. If irresponsible congressmen want to spend, they’re going to spend FED or no FED.
The FED only got involved because unemployment soared, which is what they are supposed to do. That’s their legal mandate.
My take is they acted in '08 because of rampant deflation --the Fed's primary task. Unemployment (secondary) came later.