Thanks for the reply. I don't know what to say... I'm not going to argue with your thank you letters, I'm sure your advice has helped many people! Somehow this became one of my most highly upvoted comments ever on HN, so my view of it seems to also be striking home for a lot of us.
I'm not trying to say all that matters an outsized profile. I agree that if you have that rare intersection of: 1. acing the interview, 2. a strong background with well-known companies, and 3. (critically) are job-hunting during a hiring bull market, to the point where the company cannot pick-and-choose, and they feel they must hire you, then sure, negotiation will bear some fruit. OR, if you managed to get multiple offers. I think a lot of us have never seen either of those situations.
How many people do you think would hit that bar in the industry? Hundreds? I have hundreds of letters with numbers attached to them to say nothing of how many people simply negotiate, get the comp bump, and do not feel the need to email me about it.