The primary negative aspect of Ghost jobs (from the perspective of job applicants) is not simply that it "feels bad" but that it floods the usual channels of seeking work with garbage data.

Assuming a world where there is a set of employers that would actually like to hire someone and a set of workers who are desiring employment, the set of listings that are not seeking to hire (or are only floating a job listing in perpetuity on the off-chance that some overqualified sap will take up their offer for less than they would expect in the market) encourage bad behavior from the other two parties.

It becomes substantially more difficult to parse through a pile of job listings to find what is a real (or realistic) listing and encourage the "shotgun approach" for applicants.

The flood of competing fake listings and the resultant tidal wave of shotgunned-resumes requires employers to spend more time cross-posting openings to reach real applicants and sorting through a greater number of low-effort bad-fit applications

Mild legislation that requires expected hiring dates and requires employers to say if they are just collecting resumes or face fines does not totally fix the issue but it is a welcome change in the right direction.

In addition there are direct financial costs through increased unemployment insurance claim period duration.