Correctly avoiding symlink attacks, which is the whole reason the POSIX *at variants and the dir_fd parameters were added, is not trivial in general. os.fwalk and shutil.rmtree went through many iterations before reaching a state where they should successfully avoid the problem.

Simply passing a (path, dir_fd) 2-tuple instead of a string and calling it done is highly unlikely to produce a secure result, thus rather missing the point of the exercise.