Is there a known/stated reason why Saudi Arabia did not declare itself a Caliphate?
Their closest political competitors that the Saud dynasty defeated in the 1924-25 war did claim the title of "Sharifian Caliphate" for themselves. Although Saudi Arabia is an absolute monarchy (e.g. there are no elections) and it is sometimes described as a "the Land of the Two Holy Mosques", which was seemingly the basis of the Sharifian claim to a Caliphate, the Saudis apparently avoided claiming that kind of (Caliphate) title. Is there a known ideological/theological reasons why the Saudis shied away from making such a claim?