Sorry, this is utter BS, or at least it doesn't apply to all situations.

I played exactly this script during my first interviews, never giving the first number, etc. It worked well for me exactly one time: the very first job I had out of academia where I did actually have to negotiate a salary. All the other times it resulted in waste of time and loss of sanity.

I am now very upfront with my expectations, or at least my non-expectations: "My current salary is X and I have Y perks, and I am in a good team; I wouldn't even consider moving for less than this, regardless of how cool your team is, and if you don't beat these numbers substantially I already know that my current employer will make me a counteroffer, and then you lose time but I win regardless." (of course not literally, but the message is this).

Less interviews, less time wasted.