Hi Huck,
a better way to say this is "do not place derived files into a VCS". Derived files are generated files, like object files, listing files, the produced ELF binary file, etc.
If you are using a system which generates the make files from the project file, then place the project file into the VCS, but not the make files.
Or another view is: only place the absolutely needed (source, project, configuration, etc) files into the VCS which are needed. Not more and not less.
This requires an understanding of what each file does or for what it is used for. That's why I wrote the above articles :-)