> C compiles to a binary; don't make the user compile.

C compiles to many different binaries depending on the target architecture. The software author doesn't necessarily have the resources to cross-compile for your system.

Incidentally, this is probably exactly the thing that has made most of those Python installations problematic for you. Because when everything is available as a pre-built wheel, very much less can go wrong. But commonly, Python packages depend on included C code for performance reasons. (Pre-built results are still possible that Just Work for most people. For example, very few people nowadays will be unable to install Numpy from a wheel, even though it depends on C and Fortran.)