> There is nothing stopping me from using meson, ninja, bazel, a Frankenstein shell script, etc. to build a C project

There is if you intend to use libraries as those libraries may well have chosen a build system other than the one you have chosen meaning you'd have to rewrite their build scripts. This is far from the experience of using libraries in languages with unified build systems which is typically as simple as adding a line with the version of the library you want to a manifest file.