[MrJohz]

> In reality it means the estimates can't be used for anything because they are always unreliable.

This seems like throwing out the baby with the bathwater. An unknown thing can still have bounds on it: I don't know exactly how far it is to the nearest supermarket, but it's further than 50m away and closer than 1km away. That's useful information: I know I'll be able to walk that distance, I know I can probably carry a reasonably heavy load back, and I can roughly estimate how long I'll be gone.

Fwiw, I agree with you that estimates are too often used badly by management to set up deadlines rather than genuinely make planning decisions, but I also think developers often fail to communicate their confidence levels when giving estimates. There is a material difference between "I know exactly what the problem is and what needs to be done, this will take two days" and "this looks like a pretty minor issue that will probably take two days, but it's touching a system I'm less familiar with, so it could end up going on a lot longer if strange things are happening there".