Most of what makes big companies succeed or fail is in the overall culture, organizational design, incentive structure, and corporate structure -- properties of a network of individuals rather than of those individuals themselves. I think most of Google's success and failings can be explained that way, much more so than the success or fault of employee quality.
Organizational design is really hard to get right. A senior manager described it like a herd of cats. If you get them all mostly moving in a beneficial direction, you're doing okay.
That's why they pay executives the big bucks. Executives fake understanding how to manage this stuff. Most don't, but they do a good job of convincing boards that they do.
I wouldn't care about some company's code quality but in these cases Google's clout (due partly from their maladaptive hiring practices) causes these bad libraries to get grandfathered into many projects that I have to deal with.
I've worked in companies where great programmers produced horrible code, due to cultures of optimizing to productivity metrics / features shipped, rushed timelines, and interrupted work schedules with meetings, requirements changes, and people multitasking projects.
I'm not arguing one of those is better than the other. Running a business is about tradeoffs. I am not particularly impressed with anything Google has engineered in the past decade or more. The original search, gmail, Google Docs, Android, Maps, and a few others were brilliant, but those are a long time passing.
On the other hand, I'm not ready to condemn anyone working on those over that. Competence is situational and context-dependent. I also don't have insight into Google business decisions. Google revenues are growing exponentially, so they're clearly doing something right.
Makes me curious about if you have thoughts about how to find people who are good at that stuff for real (not just faking)
Someone just released a product that offloads Chrome to the cloud. Gmail has a very long loading screen. Hangouts was replaced by something like 4 incompatible apps. Android phones are significantly less power efficient than iPhones. YouTube copyright notices are trivial to game. Etc