Expertise can be of great value, but no-one is an expert on every matter and the rest. And expertise don’t make anyone free of committing errors, or to be drawn in a corruption schemes.

We can have a thorough and deep expertise on some technical domain, and yet lake the sagacity and humility to judge where it won’t put us in better position than someone else dealing with an issue on the topic in a context the other person is already deeply acquainted with, while we are completely unaware of its many specificity.

On the other hand of course someone tightly coupled with a particular situation might easily miss some bigger picture that a relevant expertise could unlock.