Do you really know?
Because these have been the basic rules all along, never mind that the Triple Crown has never been solidified as such until the ‘70s, making comparisons even between Sec and Citation and War Admiral a bit tenuous. It can be argued that the ‘70s TCs were pansy compared to the earlier. But one thing that did not change was the openess of the races. Each horse had to face horses that didn’t race at all in the “series”.
I wasn’t talking racing per sé, just the horse culture in general. Damn near 20 years growing up in it. Breeders, owners and trainers, not to mention officials/rules bodies... Can be some of the sorriest SOB’s you’ll ever want to meet.
Especially when money is involved.
And money is ALWAYS involved in equestrian events. They don’t call it the sport of kings for nothing. And kings always wnt to win, no matter what.