Water does not wash water.
Gold is not changed for gold.
No matter how perfect we become we can not live in isolation. We need other people or our development becomes retarded through stagnation leading to narrow-mindedness which is the path away from enlightenment. The same can happen to those who only associate with like minded people. Broadening your hoizons is important but there is a danger in ‘broadening’ our experiences. When we are exposed to different perspectives, opinions and world-views we will be exposed to many truths, non-truths, and misconceptions. When we do not fully understand our own thinking or how to discern the Truth we are in peril of following the opposite or some shade of the Truth. This is the process of enlightenment, of understanding. Unfortunately we stop the search and settle in our misconceptions and half-truths forever lost from the Truth, understanding and enlightenment.