Is Zen exclusive to only Zen !@?

I just started reading the book "The Zen of Creativity: Caltivating Your Artistic Life" by John Daido Loori. In the Introduction, the author wrote that:

"In the sixth century C.E., Bodhidharma, considered to be the first ancestor of the Zen lineage, put forth the four points that define Zen:

Zen is a special transmission outside the scripture,
With no reliance on words or letters,
A direct pointing to the human mind,
And th realization of englightment.

Zen is about the experience of Buddha's enlightenment, not the words and ideas that describe it. To understand or believe in enlightenment doesn't impart any lasting strength. But to realize it - to make it real for yourself - can transform your life. The teachings of Zen always point directly to the inherent perfection of each one of us. The Zen arts are a form of direct pointing."

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Anyway, although Zen does not use scripture as a part of its teaching (as far as I know of Zen anyway), the method itself is not confined to Zen, in my opinion. Some other Buddhist traditions, though teach students to learn the basic teachings of the Buddha first, prefer to tell students that when they practice they have to "let go" of all that they have been taught as they are merely concepts made by the minds. Although they may be correct concepts, or partly correct concepts, they are still concepts, and hanging on to these concepts can prevent progress in Buddhist practice.

So Zen type of practice may not be exclusive for students of Zen, in my opinion.