Why this is true is a mystery to me. I fail utterly to see how scrum is a manifestation of the Agile Principles. In my view, scrum is in direct opposition to them, and in the end, doesn’t even remotely fulfill their purpose.
Cramming it with scrum
Everything about scrum tries to squeeze a large peg into a small hole. Scrum creates a fixed-sized hole of a given chunk of time, takes a large wooden block of effort, and tries to make a series of small, properly sized blocks fit into that hole.
Never mind that the size of the hole may or may not fit the blocks that you have. You are supposed to whittle them down so they fit, even if what you end up with isn’t really what you want or need. You are not allowed to change the size of the hole that the blocks are supposed to fit into. That block must fit into that hole, and that hole ain’t getting any bigger.