[kbenson]

If customers need it, then it's a requirement. Nothing I said indicates you should leave out customer requirements. In fact, I specifically alluded to including separate names in cases where it's needed.

Sometimes the customer is you or your org, and in those cases it may not be a requirement.

[zachsnow]

Exactly as you say: if customers (that is, the people paying for the software, not necessarily the people filling in forms) need it, then it's a requirement.

The point is that while sorting by last name (say) might not seem important to an engineer, and requiring a last name might seem outright stupid to a person filling in a form, nevertheless it is often an important requirement. Frequently folks will observe some "stupid" form, and link to some "falsehoods engineers believe about X" document, suggesting that engineering "got it wrong", when in fact they have simply misunderstood who the software is actually for.