The middle east airline transit hub model is a more extreme version of the SQ/CX model. While SQ & CX do have O&D travellers, they too depend on transit passengers and their ability to funnel passengers to and from many destinations.

EK is this on steroids. EK has far more destinations and the middle east is more conveniently located as a transit point than eastern or southeastern asia.

SIN/HKG are convenient transit for Australia/NZ <> Europe, North America <> western or southeast Asia, Australia/NZ <> Asia.

DXB/DOH/AUH are convenient transit for Australia/NZ <> Europe, Africa <> Asia, South America <> Asia, North America <> Africa, North America <> western or southeast Asia, eastern Europe <> Africa.

With so many destinations served each IAH-DXB flight is providing access to dozens of destinations (DXB-yyy) all around the globe. The same applies for all xxx-DXB flights.

Thus each market pair (xxx-DXB-yyy) needs very few passengers for loads (on nearly all routes) to be quite high.