> You need a massive amount of top notch artwork, music, 3D modelling, shader effects, SFX, etc. to have a polished nice looking game.
Top notch in any field requires optimizing hidden, underlying dependencies to deliver the best output. Optimizing code is not sufficient but it is usually necessary, especially if others have already solved it, setting the standard of performance that players expect.
The way to avoid optimizing core library code is to use someone else's library and build on top of that. But you can only do that so much. This is just an insanely hard industry to get into.