There has to be some ‘form’. Spiritual practice has to have some form to it in order to work, because the realm of formations in our own minds is the starting point we have on the road to discovering that we are more than just the formation of a string of thoughts; that we are in part beyond form, and that this beyond-form realm is the realm of Being itself. Hello, world.
It is always tempting for our normal minds to take a formation, in this case Zen, and then describe the form (using more formulations) to say why it’s like this or that. The purpose of Zen is not to be Zen-like, or even to be a perfect form (since there’s no such thing). It is in the end just a tool, a finger pointing at the moon.
It’s not even the only one, and clearly isn’t the only key to heaven.
In the same way you could study Buddhism all your life and still not get it. I even think you could sit in Zazen for many many years and still not wake up to the immediate and awesome beauty of Being. You could just do Zazen like an anally retentive robot, for example. Perfect practice. Who could fault you. Spotless action. Dead as a dodo.