Its not so they can say nobody wants to work; it’s for a few other reasons. Some benign, most not:

To suggest to potential investors that there is more growth than there really is.

To keep positions empty for long enough until they can fill with H1B applicants who would be glued to the job and receive less pay.

To simply wait for the “perfect” person to come along. A goldilocks candidate. Unrealistic hiring expectations, basically.

To always have a backlog of applicants to pull from in case someone quits or is fired.