Answer:
Ok, suppose you want to create a battery that fits exactly in the hole that is already created for an electric device, like a cellphone for example.
If the battery is slightly bigger, it will not enter the socket, and the battery will be a loss in time and resources.
If the battery is slightly smaller, it will move when it is in the socket, so the cell phone will shut down randomly when you move it, then this battery is also a loss in time and resources.
So you need to measure exactly the socket in order to make a battery that fits exactly inside of it with very good precision.
This example can be extended for any electronic piece that you need to fit in a given space (for example in microtechnology, the precision of the measures is must be extreme because working with those things is really expensive and you can not mess up with the dimensions of the pieces)
