I've talked to a research scientist at facebook who commented on this exact issue. They've debated this, the issue is that architecture, past experience, workflow are all things that can be taught to anyone.

Google and similar companies aren't in the business of hiring anyone who can just learn anything. Given enough time anyone can develop skills to be a programmer. However, google is in the business of hiring people who are intellectually superior. People who can do things that can't necessarily be taught.

You complain about 5 whiteboard problems because most likely you won't be able to solve 5 whiteboard problems. This does not mean you're a bad programmer. However, the guy who can solve those problems without an issue has a higher probability of having higher intelligence and better programming skills than you.