> Software engineering can’t be the only engineering where you ask the engineers how much something will cost or how much time it will take and the answer is “it’s impossible to know”.

Because it's not engineering at all. But even if it was, plenty of engineering projects are impossible to estimate - the ones that are doing something novel - and disliking that fact doesn't make it go away.

> Even very inaccurate estimates can be helpful for decision making if they are on the right order of magnitude

If what the business wants is an order-of-magnitude, they should ask for that; often (not always!) that's a lot easier.