You have no idea...
"Okay, we have a link on this web page, it says 'Main Menu'. Which page is the main menu?"
"Uhhh...we don't have one."
"Okay, then which page should it go to?"
"Uhhh...how about this page right here?"
"Okay, that's the page the link is on. Is that the main menu?"
"Uhhhh...no."
"Then why is a link that says "Main Menu" going there?"
"Maybe we need to create a menu page..."
"Gee, gomer, ya think????"