You are right Gergel in most cases I agree, but this guide should apply also if you have been hacked with a small account at some wordpress blogging server, or a google account.
99% of the time it's social engineering or malware that are causing the issues, but I added that step in case it is a small wordpress site or small email server, or any case that isn't specific to big companies which do have their own people to double check their security.
I'll change the guide soon to make it more accurate.