Why can't Fiat be issued by random people?
It's of course easier for government to force people to accept their fiat, but that is a technical issue. There are other ways to make people accept Fiat. Religious belief, popularity of the issuer, fear of exclusion (which is kind of force).

And what is a government? If a town creates it's own currency, is it not fiat? What about if the GNOME foundation votes on a new currency?

Fiat is Money by decree. It's easier for government to create Fiat. But it's not the only way 

 I see what you mean, FIAT was created by governments during the history, but not only, for example in WW2, in some ghettos a FIAT currency was created by ghettos authorities. In the strict sens, you have right, any community can create a FIAT currency by decree, but it's not the general concept of FIAT currency, we are talking about a nation's government not the GNOME foundation or random civilians 

 I am pointing this out because Fiat has innate defects regardless of the issuer. Which means that Monero, and certainly centralized Bitcoin, have these defects.

Monero is not the golden bullet. Gold is not the golden bullet.

Some sort of combination would be superior to both. 

 If FIAT currency (USD/EUR...) wasn't be created, there was no need to create crypto currency.

Gold / Silver is the ultimate money, can't be cheated