For those, who think there is room for optimization for C++ build pipelines and e.g. appreciate something such as the NuGet package management from the .net world, there is light in the tunnel: conan.io and meson.
With conan.io you can integrate binary packages into your build. You can either use an open server or also setup your own, e.g. in a closed development environment. Own code can be packaged and add to the server. Packages are organized dependent on version and platform, to enable cross platform development and support of different compilers. Using conan.io you don't have to install packages globally into your system (or virtualized system), which is handy when working on many different projects.
For source only packages, meson is worth a try. It allows a compact and simple syntax to include sub-projects into a project, and creates build files based on ninja.