@Kaniska you posed a good question. Nation states was a relatively new concept after WWI, I will say it was an ideology created and installed by declining Western Powers of the world at the time. From my studies about this subject the Western Powers feared with their declining power if those colonial nations rose, they would want to exact revenge. The solution was dividing these groups of people and install a flag and identity so collectively they could never pose a threat and are easily controllable factors in global politics. Muslims united created a formidable threat not just militarily but economically and population wise and most of all we had strategic depth.
The Ottoman Empire was the biggest example before it became the sick man and/or collapse it challenged Western supremacy and collectively Muslims held their own irrespective of tribal and cultural differences in its vast territory. I will even go a step further and say the Ottoman’s even administered between different sects much better – before Iraq was carved out of the Ottoman Empire they divided the territory of history Iraq into 3 semi-autonomous regions (Kurds, Sunni and Shia) as long they recognized and supported the Empire they were free to govern themselves, and the governor answered to the King.
What people fail to understand the planning was meticulous to divide the Muslim World the War Council hired the services of such people like Gertrude Bell (majority of the people I bet even on this forum never heard her name) who wrote the report that was central to dividing Muslims among ethic, cultural and tribal lands and most importantly using inner rivalries and supporting one group over the other to accomplish their goals. The likes of T.E. Lawrence were nothing, but figures people could rally around – what happened behind the scenes crafting of strategy and division was the real story in creating these nation states and installing Kings in Iraq, Syria, Jordan and Egypt.
Note: Gertrude Bell and others knew that problems would persist with these new borders she helped create but in the long scheme of things it wouldn't matter because if they stay divided its much easier to control.
If given a free choice to the Muslim World and those foreign installed governments didn't interference or repress people, Muslims would slowly gravitate towards creating a Caliphate. Other issue right now is the West arming groups that would attack civilians and disrupt these sorts of plans. Vast majority of these groups on Muslim land are foreign funded and sponsored by people sitting in London and DC.
