The author I think could phrase the argument better by saying a delivery date (something that is promised, based on quality) is more useful than a deadline (something demanded, regardless of quality).
Delivery dates do not preclude working hard and bring prudent, but they are not hard stops. Rather they are good estimations that can and often do shift.
Sales team needs that thing by December 1st? Don't ask for it on November 29th. Put leeway into the model by giving time for the delivery date to be missed. It's called contingency.
But, depends on your philosophy - move fast and break things,or deliver consistent quality code.