Most importantly, the ad should reveal the position's maximum salary, so job seekers know how much money is on the table. Ideally, median and average salaries would also be listed.
Noble goal that I feel is completely naive about human psychology.
I believe that exceedingly few of us have sufficient self-awareness and humility to see a range of e.g. "100-200k", and recognize easily that our performance and skill and history and capability is worth 120k, and will not feel scammed and underappreciated.
The prevailing wisdom on HN is empathically NOT "be happy with what you're worth", it's "ask for more more more", completely prior to any discussion of person's actual history, skillset, contribution, productivity, etc. And that's OK! We are human beings and inherently selfish and if we don't look after ourselves, who will? But it's disingenuous to then pretend that publication of a salary range will have any outcome other than all candidates expecting the top or slightly above... and I personally feel that will only result in employers pushing down the salary to match the average candidate.
If they interviewed around and all offers they received were around ~120k, then it should be a wake up call that their expectations do not match reality.