For safety, and for toilet training puppies.

I used a cage for both mine as pups, but dont use one now as neither chew, and i dont feel their safety is at risk. They also sleep on my bed, so i know if they are up to anything.

If you knowingly have a chewer, or multiple dogs that are at risk of having an altercation, then caging them when no-one is around to supervise is the sensible and safer option. Allowing dogs to chew household items puts their health and potentially their lives, at risk.
The majority of dogs will sleep through the night, so i dont see it as restricting their movements or freedom.

I dont agree with people using a cage to shut their dog away for personal convenience.