Wrong as usual my boy. That nickname is left over from the days before the Breeders Cup, when you were still wearing diapers and watching the Smurfs on tv.
In the old days the grade ones run at Belmont were the key decisive races that decided championships. Those days are gone. Champs are decided in most part on the basis of BC day. Doesnt really matter if you win the Champagne or JCGC or Turf Classic if you don't run well on Cup day.
They still call it that because it was called that for years. But the majority of champs will be crowned at CD on BC day. Thats just the way it is in this era of the BC.