There are multiple scenarios where preventing changes to the dock can be useful.
For me, this is most applicable when setting up someone like my mom’s computer. All she wants is a dock that contains the applications she needs, and one that will not change! On multiple occasions my mom has tried clicking on an application to open it…however, instead of opening it, she accidentally clicks and drags it off the dock…she’ll see/hear the “poof” indicating that the application has been removed and now she can no longer open that application.
Now with Dock Unlocker, you can lock the dock’s current size, position, and contents so that it will stay the same no matter what your mom does to it. Yay!