Going along with what Geostationary said, safety can involve things like: paying attention to your friends and encouraging those who are struggling to be heard, celebrating the cool things that your friends say, and checking in to make sure everything is going all right. The social dynamic is something that the game designer helps to construct with the rules in their game.
Any safety tool is just an abstraction of communicating your needs and feelings: if you have the wherewithal and the emotional energy, you can just say "I would rather we not do ____" instead of using the X-card, but that's not the point. The point is to give people who struggle to use those skills or who lack the emotional energy an easier opportunity to access it. Even in games that seem light or silly, there are opportunities for conflict and frustration - but there are also opportunities to practice positive skills like the ones I mentioned above.
So basically: no matter the tone or content of the game, the person designing it plays an active role in shaping how people play it. Not talking about safety is just as actively shaping the way that people play as not talking about it.