I have read that the main reason for the hyperboloid shape of cooling towers you find next to thermal power plants is because it allows more structural strength with less material. According to some sources, it also improves the efficiency of the cooling tower.
Quote from Wikipedia:
Hyperboloid (sometimes incorrectly known as hyperbolic) cooling towers have become the design standard for all natural-draft cooling towers because of their structural strength and minimum usage of material. The hyperboloid shape also aids in accelerating the upward convective air flow, improving cooling efficiency.
Intuitively, it seems like the venturi effect taking place because of the narrow throat would improve the efficiency as it accelerates the air flow and should thus amplify the natural draft. However, I have found sources claiming this to be a false popular belief.
This answer on a similar post claims:
The venturi effect resulting in the usage of this shape is, contrary to popular belief, not improving the performance of the cooling tower. Indeed, the Venturi effect increases the speed at the throat which creates a very slight increase in the pressure drop by friction on the walls. This reduces the draft and therefore the air flow available for cooling. This very marginal loss of performance is largely compensated by the gain in resistance of the shell to external winds.
(This post does not answer my question as it does not say if there are other effects at play)
And the French Wikipedia page for cooling towers reads as following:
Contrary to popular belief, the shape of the tower is not intended to take advantage of the Venturi effect. Although the Venturi effect is present at the tower neck, it reduces cooling performance very slightly because it increases the air velocity. This creates more pressure drop which reduces the draft effect and therefore the overall airflow available for cooling.
(Translated from French to English. This information is not present on the English page)
It therefore seems like the venturi effect is not among the reasons for this design. Does that mean structural strength and material savings are the only reasons for this unique shape?