My Dad told me he worked for a manager who always kept a job open "just in case" someone good walked through the door. It also made it easier to hire if he got a phone call within his network, because he didn't need to jump through hoops to open the req.
(Although it's not the approach I would take if I was a manager,) I do think there's merit in the approach. It was a real opening that could be filled, just not one that they were actively seeking people for. (IE, if someone applied, the resume would be reviewed.)
This was the 1980s or 1990s, though, so I doubt it was SPAMMed with applicants like what happens today, though.
I recently saw a project that spammed online job postings with AI slop resumes. This is great since... if your posting is slop and you don't intend to hire, you should have your inbox filled with slop. It only makes sense.
(Although it's not the approach I would take if I was a manager,) I do think there's merit in the approach. It was a real opening that could be filled, just not one that they were actively seeking people for. (IE, if someone applied, the resume would be reviewed.)
This was the 1980s or 1990s, though, so I doubt it was SPAMMed with applicants like what happens today, though.