Some languages are better supported and have broader ecosystems than others, and for a given language this tends to be self-perpetuating as a result of its effect on the languages which people choose to learn and use. This you blame on Stack Exchange? I concede the model is less than perfect, but really.

And you seem to mistake knowing languages for understanding programming. The essence of the skill is the ability to formally specify an algorithm which solves a given problem; the rest, more or less, is libraries and syntax.