[PommeDeTerre]

Languages like Haskell and Python being suitable for many applications in no way changes the fact that there are many other situations where they would not be suitable, and a language like C++ would be needed.

Keep in mind that there are also many cases that are the opposite of what you describe. I've worked with many systems that were initially implemented in a non-C++ high-level language, yet the developers had to go back and start incorporating C or C++ code at some point for various reasons, if not re-writing the entire system in C++.

The hybrid approach that Python allows for is extremely powerful, given how it makes calling down to C and C++ code from Python code quite trivial, or embedding a Python interpreter within existing C or C++ code.