Most of them are simply deprioritized and situationally used. Most companies with more than 50 employees (and less than 5,000 let's say) want something more like a pipeline. They often have some interchangeable work and might decide to hire 3 SWEs. So they interview a pool and eventually fill the 3 roles. But why take down the listing? When they post they get 1,000 resumes instantly, but every week they get 100 new ones. So if they decide to hire again they just cull the top 50 most recent and take a look. You could be the best person in the world but if you are resume 51, you are ignored.
AI (on both sides) and hiring manager laziness has made lucky timing the most important factor for any hiring chance.