This could have been written TWENTY years ago. Part of why so many jobs go unfilled while there is still so much unemployment is that HR isn’t the slightest bit concerned with attracting employers and making it easy to apply and be accepted.
HR doesn't have the same motivation that direct supervisors have. I've seen HR reject great applicants and send forward complete mismatches. I've witnessed first hand where departments would leave positions unfilled because the candidates HR sent over were completely unqualified and weren't worth the effort.
I also saw a company fire almost their entire HR team of two or three dozen. The company had hired an outside consultant to review HR's efforts and the consultant correctly reported back that for the previous two years, the HR team was so bad that even their own staff had been leaving.