Young Padawan, C++ was once a cool language, and I had to battle at multiple companies before I was finally able to make the career switch from C.
The conventional wisdom was "Where will we get C++ programmers?", "We don't have experience with C++", "C++ is too bleeding edge", and so on. The same excuses people give today to not use Rust, or your favorite hyped language.
If we follow the logic of OP, we will almost never develop new languages, because there are already multiple established languages good enough for any task at hand.
The conventional wisdom was "Where will we get C++ programmers?", "We don't have experience with C++", "C++ is too bleeding edge", and so on. The same excuses people give today to not use Rust, or your favorite hyped language.
If we follow the logic of OP, we will almost never develop new languages, because there are already multiple established languages good enough for any task at hand.