Examples of where you might use this in practice:
Generally, skip is a more temporary "lockout," as discussed above.
So why have a lockout? Wouldn't you just not program the object? Well, here is where it is useful:
If you have a trunked system and you use a wildcard (which you should be doing), you would lockout any talkgroups that you do not want to hear.
You might be monitoring a specific conventional frequency. There is interference that you don't want coming from a specific privacy tone. Simply create a new object, that is locked out, with the offending privacy tone squelch, and then your other object will continue to play all other traffic on the frequency.