Kozmo Farmgirl is also an integral part of the Kozmo deck, so players who like her art can use her all the time
They aren't "competitive" in the sense that you'd never use these decks in standard, but that's the beauty of theme mode: you'll only be competing against other, equally powerful theme decks
Take it from me, a cEDH player who, even noe, absolutely loathes fetch lands
When it's for an optional, additional cost, the extra mana feels less bad than when a card is stuck uncastable in your hand
The real selling point is getting your card back when the enchanted creature dies, giving this an incredibly low opportunity cost to play
Among the solutions, formatting the memory card is one of the available options to resolve this error