If an excellent language doomed to obscurity is one that offers "a lot of features which require a lot of discipline by the programmer," and for the mediocre-on

If an excellent language doomed to obscurity is one that offers "a lot of features which require a lot of discipline by the programmer," and for the mediocre-only mainstream languages "all their features are comprehensible by mediocre developers," then I think C++ is pretty clearly a counter-example to that, not a supporting example.