But then again, you already have a "Back to Homepage" button, why have the button if you have an "logged out" page?
Why not just direct to homepage, it's double work to make a "you are logged out page" + a button that tells you to go BACK to the homepage..
It's just an idea/suggestion to make things easy and professional for everyone.
Because the system tells you "hey, you have been logged off". Usually people will close their browser after logout, no point in send this person to homepage.
by sending someone to the "logged off" page the user got 2 options and a reminder at the same time. If homepage then its already limited for him/her to choose for. Think it like this : one way you make them think for a second what should be the next step. the other way its obvious they will leave.