Apart from not having to mess with the author's favourite build system (which probably isn't installed on my machine), I can also read the source file from top

Apart from not having to mess with the author's favourite build system (which probably isn't installed on my machine), I can also read the source file from top to bottom without jumping around between files, I also know that everything is in this one file and it's not just a wrapper around another library which does the heavy lifting. Without knowing anything about the project, or even reading the readme I just cloned and built the 'run' program, and it all took me less than 30 seconds, just finding the .c file in the project and typing: cc run.c -o run -O3