Well, that's true if your source directory is a version-control checkout, because anything else is a recipe for conflict hell as different developers use slightly different versions of the generating tools (producing slightly different output).
It's certainly not true if your source directory is a release tarball (or other release medium). Autoconf et al should have been run for you by that point, and the result tested. That way end users don't need anything but a shell and ordinary build tools to run the build. (This is one area where cmake falls down: all the builders need a copy of it.)