In a world where everyone gets a degree, someone still has to clean toilets, stack shelves, and pick litter. The philosophy of the meritocracy denies that to a very large extent the economy is a zero-sum game: yes, anyone can become Prime Minister, but only at the expense of the other 66,999,999 who don't.
An example of this would be what economists call the winner takes all effect, professor Robert Frank illustrates this with the music industry. A century or so ago, each town of any size would have a music hall along with its resident performers, some were bit better than others, but there was enough work for thousands of them to make a comfortable living. Then along comes recording technology. Now everyone in the country has access to the work of the top-notch performers, so that's what they all buy, and before you know it there's a small handful of artists who become fabulously wealthy, whilst all the music halls close, and everyone else is reduced to singing in pubs for beer money.
Of course the economy has grown, because everyone gets to listen to more and cheaper music, but wealth isn't measured in absolute terms. Nobody who's struggling to pay the rent and feed the kids will regard themselves as wealthy because they're better off than their ancestors who lived in a cave. Wealth is relative, because people compare themselves to their peers, and also to the wealth they see flaunted on TV. And that matters a great deal, because status is strongly linked to both morbidity and mortality, even relatively well-off civil servants suffer worse health if their position is low status.
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