Above is largely a myth; Typhoons in the Western North Pacific and Tropical Cyclones around Australia, and in the North and South Indian Oceans, ROUTINELY form closer to the equator than 10 degrees; in fact, 4-5 degrees is not uncommon (and some storms even reach full 65 kt+ strength while still that south.)
Typhoon Vamei hit Singapore at an incredible 1.5 degrees N latitude.
Coriolis is the same all over the world, so it's not Coriolois preventing development in the Atlantic south of 10N....likely more has to do with the location of the ITCZ in the Atlantic.
Not correct:
Typhoon Vamei: Born At The Equator
The Coriolis effect, produced by the Earth's rotation, is non-existent directly on the Equator and increases in magnitude as one travels toward the Poles.
So what caused Vamei's spin?
Analysis later revealed that a weak, quasi-stagnant disturbance off Borneo interacted with a strong, cold surge off Asia that set up a background rotation when it hit the island. When surge met disturbance, spin happened, and a typhoon rapidly emerged that had winds howling in both hemispheres.
And that is a very rare exception:
Such confluence of events has been estimated to occur once every 100 to 400 years.