Screen space ambient occlusion

<https://learnopengl.com/Advanced-Lighting/SSAO>
"Because the sample kernel used was a **sphere, it caused flat walls to look gray** as half of the kernel samples end up being in the surrounding geometry."

OK, let me assume the following facts:

* There is no absolute correctness in AO.
* I am not talking about the later improvement of using hemi-sphere kernel.

So, flat walls are 0.5, wall corners are 0.25. By **multiplying 2, they become 1.0 and 0.5** that obviously should be more correct. The question is, **why didn't they think of this simple "multiplying 2" when the original algorithm was released?**

Thanks.

RTR4: “edges being brighter than their surroundings”. Edges were 0.75, by x2 and clamping to 1.0 they would be the more correct 1.0.