Comment by lr4444lr

I think a lot of people commenting are not giving a charitable interpretation to the question. Now why any estimate is needed, but why should the dev be expected to have the right prognostication? As a dev, I have to admit it's a fantastic question. The reason estimates go awry almost always come down to things outside my control. Why am I expected to make predictions based on that? The people getting paid salaries to have a bird's eye view and veto power over those kinds of changes that could screw with my deliverable should be the ones knowledgeable and accountable for that estimate. And if I agree to it and fail to meet it, the judgment should go above both of our heads: was I delinquent, or was I blocked because someone else didn't do due diligence?