Just like how most people who ask for estimates are actually asking for commitments, most articles that state they are about estimates are actually about commit

Just like how most people who ask for estimates are actually asking for commitments, most articles that state they are about estimates are actually about commitments, including this one. Estimates and commitments are opposites - with a commitment, the giver of the commitment is under pressure to deliver. With an estimate (an actual estimate, not "I'm using the word 'estimate' but I really want a commitment"), the receiver is under pressure to use that estimate to control the project to meet its targets. That's all an estimate is good for, so there is no other reason to ask for it... which is why hardly anyone does. By definition, you can't negotiate an estimate. The subject of a negotiation is always a commitment, so if you know that the number you're going to bring to the table is going to be negotiated, make sure it's a commitment you bring, not your personal estimate. The time-honored tradition of "doubling and adding some" is simply the process of converting an estimate into a commitment before bringing it to the table.