Comment by olliej

Very thorough break down of how lighting in corners actually happens in reality, and the general misunderstanding of it in people implementing SSAO.

Honestly SSAO is just a performance hack.

But that's ok! Game engines and the like are filled with performance hacks where things can be "wrong" but sufficiently close to what's expected that we don't (generally) notice it. Sometimes it's approximations (fast inverse sqrt for example), movement (strafe + forward having faster movement), or lighting (artificial glow, halos, SSAO, etc).

That said it wouldn't hurt for shader writers to read something like this, because maybe these issues can be handled better even though the AO is still just being approximated.