Used for humidity measuring instruments primarily, like a psychrometer.
Basically using a wick or wet material and forcing air over the sensor will evaporate the water and lower the temperature reading. Compared to a dry thermometer you can work out humidity.
A very high wet bulb temperature would mean very high humidity, which is dangerous for people as sweating is less effective.
I would argue it’s easier just in significantly different ways - the Arr stack of applications take more effort to learn and setup initially, but once you have it’s absolutely effortless.