Most electronics contain hundreds or even thousands of them. Does that mean that it's acceptable for one or two of them to fail? If they did, the yield would still be greater than 99%.
For most, this would be acceptable. Some strive for even higher performance however because any number of solder failures for them is unacceptable. These cases are very familiar to me because my customers include the critical medical, military, and space device manufacturers. There is no room for defects in the products they make.
An example of a solder joint that went awry in a critical application was the recent announcement of the failure in the Hadron Collider, the world's largest and highest-energy particle accelerator. A single badly soldered connection has caused $21 million in damage that the European Organization for Nuclear Research (CERN) will now have to fund.
To read more about the Hadron Collider failure, click here.