What cromwellian said, but I'd also add that, as an outsider at least, the zeitgeist amongst people I've spoken to is that stack ranking is hurting Google.

The poisonous effects of stack ranking may take time to manifest in a notable way at Google. Maybe if Google's products stopped being as cool as they are now, or their compensation is no longer as generous as it is now (see: becoming Microsoft), this would be accelerated.

Google uses stack ranking only for calibration across the company. There's nothing like "bottom 10% get fired", and in a team of high performers it's perfectly okay for everyone to get a great performance review, so there's no politics involved in that way.

Google doesn't solely use stack ranking. Most of the grading is done on the OKR system with peer feedback.

Because they're not yanking yet and the equity growth is still attractive enough to keep unvested "low performers" from leaving. Google don't have to cut costs to make Wall Street happy. They need to grow and increase the top-line, and for that, they need people.

Once they reach the point of "maturity" where they need to minimize operating costs to increase net margins and continue to justify their P/E, they'll be like Cisco, Microsoft, Intel, and others, disgorging 5-30% of their workforce in a single massive push.