If you're learning to drive, the mechanics of actually driving the car is but a minor point, the rest is about learning road awareness, the highway code, learning how to read and anticipate situations and generally learning to be a safe, competent driver. Learning to drive in, say, a Porsche 911 adds an unnecessary layer of complexity and potential for danger so instead people learn to drive in cars that are far more forgiving. Same goes for programming. Any unnecessary layers of complexity and potential for danger only hinder the learning process, beginners have enough on their plate as it is.
This analogy doesn't quite go far enough. At the end of the day, driving a Porsche 911 in the city is really not that different from driving a Ford Focus. Also, the performance difference between languages isn't so deep either.
I would think a more apt comparison would be a Bugatti Veyron to a Formula One car. Both have comparable performance characteristic, but in a certain niche, in the right properly trained hands, the Formula One car will be superior. In other regards, and in ease of use, the Veyron will be superior. But at the end of the day, the Formula One car requires a hell of a lot more knowledge, special treatment and is just generally more of a pain in the ass to operate. On the flipside, you throw a formula one driver ( or C++ programmer ) at any other car ( language) they will do a pretty passable job with it.