It's true if you view the Higher Degrees as a means and not an end. For the Higher Degrees to be of any benifit to the Master Mason, he must view the Scottish Rite as a life-long "distance learning" program of the University of Freemasonry. And it's a program from which you never graduate: there is always more to learn, more to comprehend, more to master.
The Master Mason who views the 32d degree as a "terminal degree" and never picks up a book thereafter, never studies, never delves deeper into the teachings and mysteries to which the Higher Degrees are only a portal, has short-changed himself and may as well not have bothered.
For me, the reason to join the Scottish Rite is best summed up in the following, which is adapted from the lecture for the 4th Degree:
If you have been disappointed in the first three Degrees, as you have received them, and if it has seemed to you that the performance has not come up to the promise, that the lessons of morality are not new, and the scientific instruction is but rudimentary, and the symbols are imperfectly explained, remember that the ceremonies and lessons of those Degrees have come to us from an age when symbols were used, not to reveal, but to conceal, and that these antique and simple Degrees now stand like the broken columns of a roofless Druidic temple, in their rude and mutilated greatness; in many parts, also, corrupted by time, and disfigured by modern additions and absurd interpretations.
A few rudimentary lessons in architecture, a few universally admitted maxims of morality, a few unimportant tradtions, whose real meaning is unknown or misunderstood--these will no longer satisfy the earnest inquirer after Masonic truth. They are but the entrance to the great Masonic temple, the triple columns of the portico. Let him who is content with these seek to climb no higher. But you have taken the first step over this threshold, the first step toward the inner sanctuary and heart of the temple. You are in the path that leads up the slope of the mountain of truth; and it depends upon your secrecy, obedience and fidelity, whether you will advance or remain stationary.
Imagine not that you will become indeed a Mason by learning what is commonly called the "work," or even by becoming familiar with our traditions. Masonry has a history, a literature, a philosophy. Its allegories and traditions will teach you much; but much is to be sought elsewhere. He who desires to understand the harmonious and beautiful proportions of Freemasonry must read, study, reflect, digest, and discriminate. The streams of learning that now flow full and broad must be followed to their heads in the springs that well up in the remote past and you will there find the origin and meaning of Masonry.