This is only true if you believe recessions are caused by a lack of confidence, rather than by negative returns on bad choices.

It also assumes that A stuffs the money into the mattress rather than lending it to C, who uses the money to create something that B wants to buy.

It's a very simplistic two-part scenario and has a lot of problems, not in the least what the 'something scares A' part of it. It also assumes that nobody else wants to buy products from B.

In fact the more I read it, the less I am convinced it has any merit at all.