...by hiring a consultant. I'm a consultant. I generally work through an agency which "rents" me by the hour to a client. I generally get paid more than what a company would pay a direct employee but there are usually no benefits at all. There is no medical plan, paid vacation or retirement contributions. I generally interview via either a call on my cell or maybe Zoom or Teams. Between the markup to an agency and my premium rate, the client pays more but has much less in the way of on boarding since they can pick someone who is used to a running start with experience in their methods and tools.

So why are companies "quiet hiring"? Money! In many cases employee benefits won't start until 30 to 90 days after hiring. PTO and holidays are often accrued and, the best part, they get to skip the consultant's premium pay and agency's markup.

Big surprise, if you interfere with profits you're disposable. Companies are cutting expenses. Trimming costs at HR means they won't have folks to handle that bit of your on boarding. Maybe your supervisor is spending less time handling your issues and seeing to it that you are better utilized and more time interviewing other staff (maybe your potential replacement) and monitoring your productivity or lack thereof.

Word to the wise: consider yourself temporary until proven otherwise.

I retired a decade ago and HR was MIA then

Doesn't seem very efficient or likely to be very effective in the long run. Corporate is a jungle. Been there. Happiest day of my life was the day I retired.