I’ve never met anyone that assumed a time estimate was a, “hard deadline,” but every time deadlines are questioned, someone says, “You’re assuming it’s a hard deadline.” Can I convince you this isn’t a productive response?

Nowhere in the comment you responded to is there an implication that deadlines are “hard” (can’t be changed or have consequences for missing them). That’s for one simple reason. Everybody knows they aren’t. NASA isn’t going to launch a vehicle that they know isn’t ready. Video games, hardware, and movies get delayed. Our software project can have features cut or the release date changed. And, for the most part, it’s okay.

That deadlines are “soft” in some sense doesn’t undercut any of the substantive points made against them, nor does it actually evidence any of the claims made for them.