[qrian]

Not trying to critique anything, but it seems like engine itself is also useless without the rest of the parts.

[Avshalom]

That is point. The wheels, the engine, the frame, hundreds of other things... You can't point to one part a car and say "that's the bit that actually gets us from point a to point b"

(It's also a jab at the intellectual bankruptcy of Atlas Shrugged)

[qrian]

I am still confused. So are you implying the engineers who think they are the engine of the world incorrect or not?

[Avshalom]

Oh, Sorry. It's a really shaky rhetorical flourish if you don't instinctively associate "the engine of the world" with Atlas Shrugged, Galts Gulch and the criticisms thereof.

In plainer English: it's not a swipe at engineers, it's a swipe at engineers who think they few highly skilled individuals produce the majority of the economic output of the world.