The KC cup's purpose is to show all participants what current meta decks are capable of prior to any limitations.
If you want to perform well in the cup you have to buy new cards right now.
After the cup, you are likely not going to buy the current packs anymore, hence the new ban list.
This cup is to incite you to purchase before the ban list and the new metas come out.
What? I'm gonna entering top 10,000 with ritual beasts with less than 70 games. Did top 10,000 in April and November last year; top 1,000 at wcq with a vylon control who none of the opponents likely ever saw. Been clapping easily six sam, subterror, red eyes, blue eyes and also blackwing!
That's exactly what happen when I'm not playing a top tier deck that everybody know how to counter. Using my vylon control I take advantage on those who don't know how my deck works and how to counter it, the advantage of not being a meta sheep but still able to beat top tier decks lol