As @BCsven mentioned, the talk about stable distributions is not right at all.
Also, the commands you gave in “secure directories and dotfiles” are not doing anything. sudo chmod 755 ~/.bashrc doesn’t change the ownership of the file: it’s still owned by you. So setting the permissions 755 just makes it writeable by…you. You will still be able to modify it without sudo.
If you want to make your dotfile require root access to change, you would need to augment the chmod with a sudo chown root ~/.bashrc