Well, remember “A Piece of the Action” episode was quite believable and an example of why leaving stuff behind could poison a primitive culture (to wit, a crewmember leaving a book on Chicago Gangsters of the ‘20s/’30s). That particular planet’s inhabitants were supposed to be one that liked to “copy” things. The USS Horizon makes contact with them, they get ahold of the book (I’d postulate one of the creative people might’ve “lifted” the book) and 100 years later, the whole planet resembles Chicago under Mayors Big Bill Thompson and Anton Cermak. Yikes.
Curiously, I read somewhere that after the Enterprise encounter, where McCoy accidentally leaves a piece of equipment (communicator ?), when another ship is dispatched to “NuChicagoland” to collect their “cut” a decade or so later, they discover that the entire planet has been transformed into a fully-functional Federation Starbase, and Boss Oxmyx is now Fleet Admiral of the planet, and Kirk’s fictitious cardgame of Fizzbin, the planetary pastime.
Right, I should have cited the Roman Empire episode. ;D
I think that stuff about Gangsterland turning into Federationland was an idea for a followup episode (DS9 for the 30th anniversary) intended as a “tribute” to “trekkies”, with the aliens acting like Star Trek fans basically. They went with the tribble time travel episode idea instead.