That's a pretty naive view of things, it's not the lack of GPU standardization that drives engines, it's the fact that fundamental bits of gameplay drive very d

That's a pretty naive view of things, it's not the lack of GPU standardization that drives engines, it's the fact that fundamental bits of gameplay drive very diverse engine requirements. For instance UE3 makes a horrible engine for open-world games since it's built on loading levels whole-sale and doing very little streaming aside from textures. If you need a game that requires 60FPS(racing, fighting/etc) something that is GC based won't cut it. I've worked in in-house and external engines(UE3, Unity) and you always have to re-write large portions to make them work for your gameplay. There are fundamental tradeoffs that make it hard to do otherwise. At every project there comes a point where you no longer take unlevels from mainline, fork the code and make deliberate breaking changes to ship the game vision that was set out by the team.