I've been around awhile. And I've almost always negotiated up my offered salary - sometimes due to market leverage, and sometimes due to personal leverage. (I've also gotten prospective hirees higher pay than the offer, or even the usual band for the role in certain situations; they raised the question tactfully, and at the appropriate time.) (And no, I am not in HR, but I have hired and been hired.)
But the time for negotiation is post-offer or post-"all 68 thousand people who interviewed you think you're God, and we'd love to have you here/ HR will be in touch in the next day or so" negotiation, always. Sure, say what you make/ what you'll get if you stay where you are, or what other jobs you're interviewing for pay - when they ask. But plopping down with "I need 30% more" before hands have even left the handshake formation is stupid.
In all but the rarest of situations (and maybe for certain industries, at certain pain-point times), anyone who walks into an interview as you described would be discarded immediately. Why? Because it shows poor judgment and is off-putting. And because a) anyone who has two minutes of managerial experience knows that that person will be a whiny baby and probably an embarrassment, and b) no one wants to work with thorough assholes, or at least not with assholes who don't know their place and when and to whom to be an asshole - even when the asshole tolerance is very high and there's money to pay whatever.
I concede that if you're talking a churn & burn place with critical and understaffed projects, maybe just wants a really, really good tech monkey who will never have to interact with anyone, could be different. ...Though in that case, as an interviewer, I'd still wonder why they had to interview for a job that is up-front advertising so much less than they want to get. But I get it: desperation, deadlines, and expiring budgets can make a smart (hiring) man make foolish choices and decide to deal with the fallout later.
Speaking of time and place and the wages of unvarnished arrogance: I still remember the guy who came in at a place I worked once. At the time, we paid top of the market in the top market, so very selective, but the place was growing FAST and was very aggressive about hiring, because they needed bodies - capable bodies, but bodies. And this guy came in as a very desirable hire, was given excellent pay and prospects. Within a week or so of starting, he was barking to the CAO that his office ceiling tile count was slightly lower than an existing employee's, despite that other person's being junior to him in experience (but with a few years at the place) and title designation. (Iirc, there was a support column that protruded slightly into his office.) Literally demanded the CAO come into his office while he pointed and counted and yelled about it.
He didn't last a week after that tantrum, need and talent be damned. ...And that place was (almost necessarily, tbh) full of assholes, so it was not a matter of delicate sensibilities. But there's a time and place, and walking in the door acting like a BSD isn't it, much less slinging demands before they're committed, and absolutely not at your screening or first-round interview. Not in 99% of situations.
All that said, totally agree that your in-the-door price is important, and I, like I said, have almost always negotiated up (not 30%, bc again that shows immaturity, deceit, and a mismatch at best). It's important to see what you can (reasonably) get once they want you, if you have any leverage at all, because in most types of organizations (other than those with lockstep increases), this year's salary is commonly bumped by a (low, though slightly variable for exceptional employees) percentage to get to next's, and absent a formal promotion, those increase % bands typically suck ass.