Why do microwave ovens use 2.4 GHz like WiFi and Bluetooth?

Microwave ovens that you use to cook food use 2.45 GHz. This is the same radio band where one finds WiFi, Bluetooth, and so on. So, why is everything lumped into this one chunk of the frequency spectrum? Is there something particularly magical about 2.4 GHz? There is a common misconception about this frequency and water. The truth, however, is far more mundane...

An article about 'Electromagnetic absorption by water' that will make your brain hurt:
https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_water#Rotational_spectrum

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