People of lower economic circumstances may not have had access to computers prior to college.
In 2010? This article is supposed to be about US, not a third-world country, right?
I don't for a minute believe it is necessary to have been coding since you were 12 in order to do most jobs in Silicon Valley. But if companies decide to discount people because of it, then you will absolutely filter out people who come from lower economic backgrounds.
This is a great example of institutional racism.
All of it ends up affecting their hireability.