Earlier quoted context omitted.
Maybe. But it's more likely they're replacing shaders with game- or engine-specific workarounds for hardware bugs. Used to do exactly that in my first GPU driver job. The goal wasn't to cheat, but to fix issues in popular games that for one reason or another wouldn't be patched for your GPU on its release.
I wonder why they don't just call the game developers on the phone and say "here is AMD, you must fix your shaders, here is the code". Certainly I would jump if I got contacted by AMD or NVIDIA. Now someone is going to say, if a game breaks people are going to blame AMD, so it is their problem. But AMD would just have to play hardball once, pick a smallish publisher and say "XY refuses to fix their broken code, we ev…
• Old games. People still want to play these, even though the developers don't maintain them, or no longer exist.
• Game engines. If there's a bug in e.g. Unity or Unreal, that means an unimaginable number of broken games. Likewise for middleware. And it's not the engines or middleware devs who pay the main cost here: all the games using them must be updated. Which may be quite difficult if e.g. the fix is only in the new engine version, but a game project is using an old engine version, and there was some backwards-compatibility break in-between.
• Competition! If one GPU vendor doesn't fix things, its competitors will, and it will lose customers because consumers (rightly) expect that any GPU runs any releases game.
• Gamedevs may not be able to quickly or easily fix a bug. Also bear in mind that in traditional game development, once the game ships, the team is wound down. There's nobody — and no budget — to maintain it.
• New hardware. Gamedevs can't test against your next-gen GPU that hasn't been released yet. If a bug only causes problems on that hardware, how do you get them to fix it and prevent it reoccurring?