The game already has promised that trading will arrive in January, and there have already been unique events that have aimed to help players get certain cards
With Gold Sarcophagus, you can add spells, traps, monsters, whatever you need to clinch that victory
You dont need to take every legendary card you see, either, meaning you can dig through the top of your library for that Piru, the Volatile, make the rest into Treasure tokens, and ramp into dropping your huge dragon way early
The most obvious thing Kaiba had going for him in the original series was boasting some of the best cards in the game at the time
It however is still considered to be in exile and not on the battlefield or your hand, meaning that there are much fewer ways for your opponent to be able to get rid of it before you can cast it