Going back to the original answer - you will find these behaviour in every programing language forum.
Stack overflow downvote trivial qustion so Stack overflow stays "Professional-oriented" Q/A site. other forums don't filter out beginners questions so it seems like they are "Beginners oriented".
the truth it that in every programing language most of the people start learn programing for some reason (own interest,school,university) but they quit somewhere very soon after their course ends/they fulffiled their inner curiosity.
you will always find more beginners than intermediate developers than advanced developers, and this is the precentage of questions you will usually find.
the truth is that I prefer ask a question here than stack overflow because here I can develop a serious discussion on the question wheres stack overflow has more "find the bug" niche.
and C++ is nowhere close of dying. everything is implemented (eventually) in a native code. this include OS/Compilers/Language extensions. not to mention the thousands of desktop applications and triple A games.
C++ even gains some of its popularity again with the new standards of 11 and 14. many major companies keep their support in C++ ,for example Microsoft published a new and modern way to develop windows applications with Windows Runtime.
so you can see nothing is "dying".
I keep telling my JavaScript-developers friends "you can do what you can with JavaScript only because some C++ developer exported this functionality out".