Most PIPs are designed to provide a documented reason for letting someone go that can be used to contest any possible lawsuits. They are not necessarily designed to help people. Some are, and some managers believe in them.
Unless you are in an "at will" employment state or otherwise fall under those rules, then the company trots out "at will" (which you signed an agreement to) then the HR DRONES will state "You have no grounds to sue."
In e.g. Texas if they fire you without properly documenting a flimsy non-protected-class-infringing cause, you may be able to draw unemployment. I don't know what the success rate is like for IT workers.
Unlikely tech firms care about unemployment. They care about 10 million dollar sexism/age discrimination/racism law suit
“At will” employment means that you may be fired for any reason or no reason at all, but not for an illegal reason. It’s a fairly meaningless term except insofar as it indicates you aren’t under contract for a specified term.