Earlier quoted context omitted.
In order to have an effective meritocracy you have to have universal education. You then pick the top 0.1% and invite them to join you and marry your son or daughter. The whole economic system is designed to identify the very clever no matter their background and bring them into the ruling class.
If we build upon your assertion ("to have an effective meritocracy you have to have universal education"), if some of those in power define universal education differently (which would seem to make any concept of universality in education void of such in practice), then it wouldn't be surprising to see a decline in the effectiveness of an economic system, which is what I would suggest is what we are seeing today.
If you want to be really clever you just give those smart kids who had a bad school environment bonus marks at the university entrance stage and give full scholarships - say just like the elite universities do right now.
I should mention the aim of the rich is not to maximise production, but their share and status. It does not matter if the pie is smaller as long as the size of your slice is larger.