Sutras good for?"
Before we get to that question, let’s look at Buddhism in general. Zen is waking up to our original nature, not our original Buddhist nature - So why Buddhism?
Since the Buddha woke up over 2500 years ago, the Buddhists have been helping people to wake up. They have also been writing about it. The writings have taken many directions. A few examples: Some writings work to dispense the wisdom people have found when they have woken up. These teachings can help us by give us focus on correct direction. Some teachings try to point the way to help people to wake up. These teachings give us hard earned knowledge on how to practice. Some teachings sort of mix the two by providing abstract concepts that cannot really be understood by the thinking mind. These teachings cause great confusion, helping us keep don’t know mind.
Many of these Buddhists who came before us spent most of their lives as full-time Monks. They spent much time practicing and passing on what they learned. As a result, there is a huge storehouse of knowledge in the Buddhist Sutras.
For each of us that turn to Buddhism and meditation, we get exposed to many of these teachings. We can then see which types of teachings resonate with us. Even those of us who gravitate toward a certain type of teaching can still find use in many of the other types. Also, when we encounter people who are interested in Zen, we can gauge their leanings and introduce the types of teachings that may be most useful to them.
As Zen students, we see that Sutras have their place and we don't get hung up on any of them or treat them dogmatically. In fact, a single moment beyond words is worth more than any Sutra. So we treat them accordingly. Here is a short gatha from one of the Korean masters (Sanshan (Denglai)) from long ago:
Talk produces many lifeless but marvelous meanings
The tip of the tongue lacks bone but bears lies
So to accept words and stick with sentences ultimately is of no use
And what can you do with a frozen mind?
What does this mean?