Difference between Auto Forward Emails and Sending Emails to project

I was reading the link below on integration with email:

There is something that is not clear to me. If I can send emails to projects that will be turned into tasks, what is the advantage to do the procedure described in the “Auto-forward Emails” section.
I understand the advantage of setting rules on the email client side, but that can be done to forward e-mails to the project email as well as to the forwarder@.
Have I misunterstood?