"Slower" is doing a lot of work there. It's the difference between an engineer or two wrecking havoc doing a major refactor and convincing a manager that it's ok while you're away on vacation, and the same engineers failing to convince the manager because it will take forever, and quietly dropping the project after hitting the first roadblock.

"How long is this going to take?": "a week" vs "a quarter" makes a huge difference.

Extreme speed is a form of quality; the fear is that it enables bad things to happen.