You are absolutely correct. The effects of Saturn per se only set the stage for possible growth via the energies of other planets. But then as my aunt used to preach to me, "God don't give you no burden you cain't carry." She was a simple country girl, so she talked funny. But she talked sense.
But the idea is that Saturn's effects are part and parcel of the whole chart (the whole personality) and specifically designed to be overcome, resulting in growth. They present you with a "reality test" that brings you to ground where you can begin to build your life structure on a foundation of realistic rock rather than delusional sand. Whether one passes the test may be a matter of choice (free will), or may not. The jury is out.
Saturn is more than what we have been discussing in this thread. He is the planet that defines our identity, because he isolates us, sets us apart. He brings trials for us to overcome, and in doing that we become what we were intended to be.
I think I have written here before that it apalls me to see this world of people who will pay any price to avoid pain (e.g., our addiction to mind-numbing drugs as a means of escaping pain -- there are also other escape routes). Pain is a very necessary part of life. Without it there can be no growth. And that is a simple inescapable truth.
I first learned this as a kid on my high school swimming team. Workouts were pain. You swam far enough and long enough to meet pain, then you kept swimming right through it, until you came out the other side. When we got cramps the coach would holler, "Swim it out." When you got to the other side of that pain, your performance was enhanced and what had caused you the pain could never do so again. Through pain, you had grown in stature.
If Saturn symbolizes discipline and hard work, which it does, then the value of it can be seen in this example. Saturn is duty, obligation, responsibility, and also the wise old man who's "been there, done that" and knows about pain and suffering and its rewards.
And so in a sense you are not absolutely correct. Pain and suffering, frustration, restriction and limitation and such other unpleasantries as Saturn carries in his bag of tricks bring their own rewards, in and of themselves. It is the growth of consciousness and understanding, and the realization of who and what we really are.
Saturn was the Ring-Pass-Not of the ancients. He was the Keeper of the Gate, and only through his auspices could one pass beyond, could attain eventual freedom through self-understanding. The Bhagavad Gita says that "all men are born in delusion." But it is only through facing reality that we become free and can walk in the Light. Tezcatlipoca, one of the principal gods of the Aztecs, carried a smoking mirror (which is what his name means) that he used to make his enemies see themselves as they really are; and in doing that he defeated and utterly destroyed them. If we are to succeed in life that is what we must do: Look at ourselves in the Smoking Mirror. Saturn enables us to do that, for he is the planet of stark reality.
