He only has authority to "cancel" debt that is owed to the federal government. It neither needs nor uses revenue, so it's a no-brainer way to generate stimulus. Canceling private sector debt would require spending authorization, which, as we have seen recently, would not be possible in today's corrupt congress.

However, if he does that it will come dangerously close to disclosing many secrets of government financing and monetary policy that his donors can't afford to have disclosed, and both parties perpetuate. If the people ever figure out that their government is the sole creator of net money in circulation it might piss them off considering the lack of benefits the working class has suffered for decades.