You may be right. I truly think the horses and the bulls enjoy it though. I don't know any bulls but I've known some horses who get the greatest enjoyment out of trying to dump a rider.
Eh... maybe.
Still, I think if the contest were to ride the unbroke horse without bucking strap, until he stops bucking... with the effort of the rider working to settle instead of increase the amplitude of the fight, it would be a test of a real valuable skill. Course, they could only use a horse once, if they were any good. ;~D