They hire people who can pass algorithm tests, those same people once employeed game the performance review process. You can't fire them because they "meet expectations" but they also have no interest in maximizing their impact towards helping the company succeed.

For example, if the company gives you a goal of contributing to OSS you could add some feature that no one asked for and contribute 200 lines of code quickly. Or you could debug and fix a bug that many people complained about and that may take much longer and may be just a one line change. But your manager doesn't have the time to drill down into the details of that on your performance review. So the bug fixers looks worse than the feature adder during performance review.

You could say the problem is management for having a bad review system but as soon as they update the review system it will be gamed by the people who don't care about the company.

This is a side-effect of hiring smart people to do simple work.

These companies optimize for hiring people who've spent their live trying to beat the next "level" of their lives with a bigger score than all of their peers. And once you have them, you make them QA the game of life on easy mode. Some people will invent some meager challenges to stay sane, and others will just be bored and miserable without a challenge and the prestige that comes from overcoming them.