-There was a power vacuum in a region with a pretty high population large part of which was trained in constant warfare for generations.
-Thanks to islam they had less problems with stabilising the eastern frontiers and push to balkans.
-They managed to create a non-feudal state aparatus inspired by byzantine (timariot system) and smash the turkish noble families which allowed to concentrate insane amount of power and wealth in the hands of the Sultans without anyone in the state to challenge it.
-They were a lot like todays woke corporations who understand that diverse population is a divided corporation and used it to own advantage, Romans did the ottomans were more efficient. https://journals.openedition.org/ejts/4396
- When you look at their elites they were very cosmopolitan, by design, they extensively used christians and converts in high state positions (like the notorious fanariot greeks who ruled Wallachia for them).
In short for a period they were highly militarised and highly efficient state thanks to decades of warfare and remnants of roman beaurocracy and ruling techniques.