Remember the days before computers and the internet? Back then HR was dealing with an meaningful task of keeping employee's files, sorting applications, posting jobs, writing job descriptions.
Those days are gone since all their work can be done by computers with an insignificant amount of maintenance needed. All postings are done on the jnternet and applications could be automatically scanned.
So what do you fall back to, when your value contribution vaporizes? You counter attack by artificially blowing up your importance through the introduction of bureaucracy, processes and redundancies.
They make you jump through hoops, humiliate you with personality tests and fake job add pay ranges just because their whole existence in the corporate world is build on smoke and mirrors.
GFY HR!