I work in high-end data infrastructure, not games, but almost identical incentives and dynamics are at play. The state-of-the-art research isn’t coming out of academia for the most part. The R&D being done in private industry is slathered in NDAs that only slowly leaks out a decade or more after it was put into production. Many people don’t stay with it long enough to really master it.

There are some elegant and sophisticated techniques related to database kernels that have been passed around for a decade or two over beers that still don’t have a single reference in literature that I can find. The original researchers probably stayed quiet because it was under strict NDA but also likely retired years ago. No one writes it down because it sort of feels wrong to claim second-hand knowledge of unknown origin as your own, or to even lead people to assume as much. You show people, and they think it is amazing, but when they ask you for references or sources you have no idea where it came from.

There is a real gap here and it is getting worse.