I have no idea why that's spoilered but;
The Eldar have been without the Old Ones for something like 50 million years. They are also fully intelligent beings, unlike the Orks who are forced into a genetic disposition to act a certain way and to know certain things. They were certainly designed/uplifted by the Old Ones but they weren't designed to be a weapon like Orks were.
So basically there is no reason for them to be without scientists. In fact assuming they are without scientists would be just weird if you think about it.