It's because in Call of the Wild Scenarios, the Keeper Actions cards aren't revealed until the first time the Keeper uses them. So hide that Command Minion! You don't want the Investigators knowing how you can move monsters!
So is the new set of action cards, and keeping them initially hidden, transferable to MoM and FA? Or is this method and set of cards exclusively for use with CotW? The rulebook seems a little vague on this....unless I am missing something right in front of me.