Welcome changing requirements, even late in development. Agile processes harness change for the customer’s competitive advantage.

This is what most people mean when they put in air quotes "Agile".

A blessing and a curse, we use this to make our product more nimble and responsive, but in truth, we use it to excuse sloppy prioritization and execution when we allow new requirements to be suddenly added to the pile at any time.

This principle is important in fighting the tendency to oppose change because we are already committed to a course of action or architecture, or afraid to admit we did it wrong (in every area of the business).

Remember that the very processes inherent in scrum, kanban, lean, etc, are purpose build to eject what's not working, and reprioritize and rescope work based on the new reality on the ground.  The perception that changing dates and scope is still a big no-no is what causes resistance here.