Decades ago, Google had great engineers. Today it makes money through near monopoly businesses. It's maps product, for example, hasn't improved in years and has some glaring flaws. Anyway, those who work at Google want to believe Google is special because of them, that Google was built by great test-takers. It wasn't. Today, Googlers spend 30% of their time humiliating applicants, playing games on their computers, and the last 30% doing a little work.
Creative and passionate people no longer end up at Google. They go elsewhere and build the businesses Google can't do and might buy if it fits into their monopoly.
Everyone would love to have Google on their resume. Everyone would love to have the money. But if you can't suffer the opinions of people who pretend they're better than you then you go where results really matter.
Ultimately, no one can identify good developers. You give them 3 months and see what happens. Or you look at what they've done already.
All companies rise and fall. As soon as a company like Google believes their shit doesn't stink it's downhill. The best thing Google does for society is inspire our future doers. It hires followers, not leaders.
PS, don't get me wrong. I use many Google products and in general love the services. But the best young devs I run across no longer end up at these companies. So I can only assume who does ;)