Yup, there’s still a video on YouTube somewhere of Alan Willard demonstrating SVOGI using Elemental Demo assets (which IIRC, was running on a 3 SLI’d GTX 680’s at the time). They later realised it wasn’t viable tech for everyone (initially due to this generations underpowered consoles), so they dropped it.
It’s been explained a few times in the past. VXGI is a faster version of SVOGI anyway, so in the long run we haven’t really lost anything, other than it not being in launcher builds.
I seem to remember a lot of negative talk about the engine at the time, and how it had prematurely lost the “engine race” of this generation due to removing SVOGI entirely. Lol… look whose laughing now.