Many popular languages nowadays essentially have just one viable open source toolchain: Go has the Go toolchain (gccgo being niche), Python 3 has CPython (Jython and IronPython only support Python 2.7, and PyPy is not up-to-date), Swift has the apple toolchain, Haskell has GHC (none of the other compilers is widely used).

That's not necessarily a bad thing since the compilers are all open source and you can port them to whatever platform you want anyway. C managed to spawn a lot of adequate compilers, but the language itself has seen very few changes since it was standardized (27 years ago), while all the other contenders (including C++!) see a major release at least every 2-3 years, and up to several times a year (for Rust).

You can't have that pace of changes and still maintain compatibility between all the different implementations.