This is completely untrue.

Bitcoin Core does not use the latest C++ nor the latest boost versions nor even the latest gcc. Bitcoin Core currently uses C++11, but the latest is C++17. The current boost version used is 1.64 which was released more than a year ago. But using newer versions of boost should still work.

It can also be used with different compilers such as clang and Visual C++. There are even instructions, project files, and a CI system for using MSVC and Visual Studio! Furthermore, building with clang is supported too.