Just to offer another view.. Pin locks are designed for removable but permant socket retention. You need a tool to remove the socket so it cannot accidently fall off. They are used for production lines or anywhere when having a socket fall off can lead to bad things. Working at heights is another area. Tower workers, lineman ect. They also offer flexibility so you can use different sockets under more than one application when it's cheaper to do so. I have impacts at work that use 5/8 hex chucks, and other that uses 7/16" hex - both with locking quick chucks. I can buy a regular mechanics style (square drive) socket and just swap adapters on the socket to use with different drive style.. So on a single 1" socket, I can't swap out a 7/16" hex to 1/2" square adapter, a 5/8" hex to square adapter, that both use pin locks so the socket can't fall off while I'm using it - and then later take the adapters off and use that same socket on a regular ratchet.. The alternative is buying single, one piece sockets that have each adapter machined onto it, ($200+) which gets very expensive instead of just buying $20 adapters and using one socket.
I have smaller pin lock adapters from apex that I use on a 12v impact driver and 1/4" square drive impact sockets. (instead of a square drive impact wrench) . Using the impact driver with a locking quick chuck, I can use the pin lock adapters so that the sockets CANT fall off 20 feet in the air - but I can quickly swap out to other size sockets that have the same adapters on them using the locking quick chuck on the impact driver, instead of having to stop and get a tool to remove a socket from an impact WRENCH that used a pin lock.
Here's a good pic of the pin lock opposed to a ball detent. Only impact sockets (usually) have a hole in the socket on one side of the square drive so you can use these..
