>This sounds more like an excuse rather than any sort of rational argument as to why game engines can't be open sourced. The reality is that there are plenty of projects out there helmed by incredibly talented engineers with extremely high level knowledge that exist in the open source realm; one only has to look at the geospatial community to see this.
I'm not saying there aren't talented developers working in open source. But the sheer breadth of expertise required is unimaginable. You need top-of-their-field engineers from practically every conceivable discipline within CS to build a AAA game engine. Physics, lighting, rendering, networking, audio, UI, and that's just the tip of what I can think of. Engines like Rockstar's RAGE are easily on par with the Linux kernel for complexity.
I'm not saying there aren't talented developers working in open source. But the sheer breadth of expertise required is unimaginable. You need top-of-their-field engineers from practically every conceivable discipline within CS to build a AAA game engine. Physics, lighting, rendering, networking, audio, UI, and that's just the tip of what I can think of. Engines like Rockstar's RAGE are easily on par with the Linux kernel for complexity.