"CMake is an open-source, cross-platform family of tools designed to build, test and package software. CMake is used to control the software compilation process using simple platform and compiler independent configuration files, and generate native makefiles and workspaces that can be used in the compiler environment of your choice."
Cmake is a makefile generator. The output of cmake is a series of makefiles. That's it. If you need to build a project and you don't have make, nmake, jmake or whatevermake in your system them cmake does nothing to get your project built.
Although you're conflating project transcoders with makefiles, nevertheless that's the whole point of cmake: generate makefiles that are used by some third-party program to actually build the software.
Leveraging compositional abstraction doesn't change what you use the thing for. I use cmake (well I don't often, but when I do) to build my projects. How it accomplishes that is if little concern.
Yes exactly when you remove a piece of the build system the build system stops working.
When I use bazel I need python installed or it doesn't work. That doesn't mean my build system is python. It means my build system takes advantage of python. Same for cmake and make.
Yes. Make is a build system. Cmake is also a build system that leverages make. This means that from the perspective of a user of cmake, make is a component/dependency/part of cmake. make can be used independently, and is absolutely developed independently, of cmake.
But when you remove a dependency of a tool you can expect the tool to stop working. That doesn't mean that the tool doesn't do what it says it does.
They would disagree with you.