On a bare POSIX system thing like CMake first needs to exist there to work. And it isn't in spec. Autoconf emits a source distribution that's build-configured

On a bare POSIX system thing like CMake first needs to exist there to work. And it isn't in spec. Autoconf emits a source distribution that's build-configured using a famous 'configure' shell script. Since POSIX is still a thing I wouldn't even put autoconf as outdated. It still has purposes. For example I'd say that outdated tech would be running your website using CGI, preferably using C backend for extra mushiness.