Much like Up the Beanstalk of Modern and current Standard fame, Yshtola only cares about the printed cost of a card, not how much you actually pay for it
Precons come in various power levels, with some weak, and others as strong as constructed decks
Don't forget one category of cards that benefits from players not casting cards for a turn are werewolves from the original Innistrad block of Magic sets
Supply outstrips demand so much for these Intro Pack cards, especially gold five-drops that will only see play as a two-of or three-of in one deck as a best case scenario
The selection almost always includes a mixture of brand new cards (where the card name, in-game rules, and art are all new) and 'reprints' (new versions of existing popular cards, which keep the same name and rules, but may feature new artwork and sometimes updated wording)