Just a further point, often the both you and the customer agree that there is a problem that needs addressing, but the customer is not sure how it should be solved. Alice from accounting wants the system to do X, while Bob from compliance needs it to do Y, which directly conflicts with X. Finally Carol in management has determined that they are not going to pay for a solution anyway.

This is exactly the 'crap' that you need to shield your developers from. Shielding developers is a lot deeper than just ignoring requirements.