Some work needs quoting before it starts. Quoting and confirming are now separate, recorded steps rather than an informal conversation.
Quote First
Send a quote to the customer and leave the order in a quoted state, so nothing is scheduled or started until they say yes.
Confirm When They Accept
Confirming the order is an explicit action that moves it into the workflow, giving you a clean point where the commitment was made.
Returns, Voided or Reverted
A sales return can be voided or reverted, so a mistake in processing one does not have to be corrected by hand.