There's one important question left out: what kind of games does the author make? I can see how 'vanilla' C can be more than sufficient for basic 2D games, but as soon as you grow in complexity it can quickly become an insurmountable task to grok.
The Unreal Engine is around 4 million lines without dependencies (e.g. PhysX, a proper audio engine, etc). You could try to do all that in C (good luck finding a good physics library with a plain C interface, btw.). But you need to have proper software design throughout the project and you will likely end up replicating some kind of inheritance or polymorphism scheme somewhere.
The Unreal Engine is far more than a modern game. You wouldn't call Clang and editor just because Vi was compiled with it.
And Quake 3 was made by a team of roughly 20 people. Id Software was quite small until they started to work on Rage.
And there's still plenty of life left in 2D anyway. Not everyone wants to crank out the next Fortnite or whatever the kids are into these days.
Civilization.