We need to expand the set of possible actors and goals. The anthrax campaign happened immediately after 9/11. The result of the campaign was the end of effective political opposition to the massive expansion of military and "secret" aspects of the USA government made possible by 9/11. Cui bono? Certainly not the several implausible patsies the authorities immediately had lined up to blame.

Numerous USA calamities make a lot more sense when we study them with an eye toward who benefits rather than who is blamed.