Sure, they had a system of relatively successive monarchies, but that isn’t the same as having a single running system of government. And it certainly not somehow more legitimate than theocracy, if your own benchmark is democratic rule - which you just said was the determining factor of a government’s legitimacy.
Also, not for nothing, but the last monarchical dynasty was literally installed by the British, and propped up by Western powers until the people, or at least, a fanatically religious subset of the people, overthrew them.
Again, it’s not like I’m a fan of theocracies, but saying that their current government is illegitimate is absurd, whether viewed in the context of international relations, or internal support and control.