Recent versions of several Linux distributions and FreeBSD have made newer clang and g++ versions available, which both have decent support for C++17 features.
For example, Ubuntu 17.10 provides clang-5.0-3 and g++ 7.2.0. Installing clang 5 there is as easy as
sudo apt install clang-5.0
It's also easy to install various compilers side-by-side there, without messing up the entire system.
For die hard everyday C++ development, one probably does not want the C++ compiler run in a somewhat restricted container and experience all the potential trouble and limitations.
However, containerizing the compiler is a good way for providing a standardized build environment, because one can pin the exact versions of the compiler, libraries etc.
I have also seen people moving all their not-so-important stuff and/or the components that they do own maintain themselves out into Docker containers, in order to keep their base systems lean and clean. And so they can get rid of the containerized things easily should they become irrelevant. Plus keeping the containerized things relatively stable and unaffected by changes to the base system.