I hope this helps explain it better:

So for example, in my multisite network I couldnt lock the pages by ID, because depending on when the pages are created, it may not be the ID for the page I want to lock, however I could make sure that certain permalinks are reserved for the multisite for the locked pages hence why I’d like to be able to define the (reserved) permalinks for which are to be locked.

I hope that makes sense 🙂