Yes. Getting hired by Google is only part of the deal. Actually _succeeding_ when you're already there is much more difficult. It's a high pressure environment with a lot of very smart overachievers. Because of this it's sort of a self-fulfilling prophecy, and people who don't measure up also don't feel welcome, as it were. Since performance reviews are largely derived from peer feedback, hiring mistakes tend to be self-correcting. Most of the time, though, I've seen great people leave just because they didn't like the pressure. The amount of pressure depends on the team. The higher the profile -- the more pressure (but also more rewards, greater career potential, etc). But the general bar for what's considered "good work" is pretty high, and more uniform than in any other large company I have ever worked at.
Then there's the issue that by the time you even get an on-site, you're already very much not a random candidate. Recruiters actually do look at your track record, etc. You can bullshit there, but I don't recommend it, since references will be spot checked, and they better line up.
Google interviews are largely a roll of the dice above certain level of basic engineering competence. I.e. if you don't know the basics, you will almost certainly not pass them. But if you're a more senior candidate, Google doesn't really know how to interview you, and their interview process turns into a random number generator biased heavily towards "no hire".