The premise of the article is that good education is available to some and not others, and that their children are more likely to also get good education, thus perpetuating the gap.
This leaves plenty of intelligent and meritorious people with poor educations and thus poor prospects, which tends to carry over to their kids. The very opposite of "meritocracy".
The article more than once calls for improving the prospects of poor, clever children.† If you missed the emphasis on intelligence, I suggest you give the article another read.
† — In Britain, where the article was published, clever is very nearly synonymous with intelligent (and more often used), by the way. Americans tend to use clever to mean something more like witty, inteventive, or even cunning.
> The link between parental income and a child’s academic success has grown stronger, as clever people become richer and splash out on their daughter’s Mandarin tutor, and education matters more than it used to, because the demand for brainpower has soared.
> The solution is not to discourage rich people from investing in their children, but to do a lot more to help clever kids who failed to pick posh parents.
> Improving early child care in the poorest American neighbourhoods yields returns of ten to one or more; few other government investments pay off so handsomely.