Heck with it.
One day I am going to going to let my players in whatever D&D-type game I am playing at the time use WotC's Fortune Cards, Paizo's Game Mastery card decks and maybe I'll through in some Tarot/Tarokka Cards and the Deck of Many things all in the same game.
And I'll let my "Boss" or "Big bad" monsters have the same.
What the hell right? It should be a blast.