Some were short. Some lasted for decades. As an example the 30 year war.
Fiat makes financing wars easier. But not to such an extend that without it there will be less wars or that they will be shorter.
Even if without fiat politicians will be forced to compromise (there is no historical evidence to support this, but let's assume it's true), that is not necessarily a point against fiat.
If the US would have been forced to compromise with Nazi Germany, is that a good thing?
