You don't get it. Silicon Valley is WHERE the large companies are based. That's where decisions are made. Do you know how many millions of employees are employed by tech companies based in Silicon Valley? Not to mention how many companies are in business solely because these large companies use them as contractors.
My issue with the article is it is taking a national stat (graduation rates in the US and CANADA) and then extrapolating from that data to apply it to only silicon valley. Its faulty bullshyt.
Secondly, while Silicon Valley is the hub of technology, which I'm not disputing, the issue here is that is being used as the SOLE gauge of success which is a false way to view this. Again I believe the media and folks who only follow corporations with high profile names like google and yahoo have a very myopic view of what constitutes success among those with degrees in engineering an the like.
Also a lot of these companies are global. While their head offices are in silicon valley, the often employee a sizable amount of employees in satellite offices.
One last thing that sort of get lost sometimes is that there are a lot of companies that are not even "Tech" but still require those skills for certain aspects in their businesses.
Silicon Valley while is the face for the Tech industry to the public at large, its not the end all, be all by any stretch. Otherwise, again, every person with a STEM degree would live in California.