What I mean by that is that these are cards that require a way to physically track which rooms are unlocked in every game, and if you're using something like a die or a coin, those can be bumped onto the opposing room, making things a bit confusing in longer or more complex games
or who soul-read their opponents hand, card for card, the entire game
In a manner similar to minted coins, historic documents, and even Beanie Babies tags, there have been many Pokmon cards with errors and these errors have impacted the value of particular cards
Obviously not all colours have access to such things
In the context of Danger!, this is a good way to discard something like Danger
Cards printed in the last couple of years (from the original Modern Horizons forward) take up such a large part of the metagame that the format is almost unrecognizable, as compared to where it was a relatively short time ago