Crucial?

I read this comment about the literary and historical context of some of the New Testament letters:

But the epistles themselves don't leave many explicit clues, and since a lot of scholarship discounts patristic testimony and limits itself to internal literary evidence, it is hard to be certain of a great deal in this crucial area.

But if the epistles themselves don't give clues, and internal literary evidence doesn't answer the question either, then how is it 'crucial'?

Answer? It's not.