Well this was life; die today and life would still go on, time wouldn't stop and not to talk more of people who were mostly fake. Even those who really had a bond with you would only slowly diminish that connection untill its forgotten.
Even the bonds in the strongest metal—diamond—could be broken with time and intensive heat, so why wouldn't people get detached?
But this was why people had a name. Because legends never die. At least their name doesn't.
Yes, Allen was gone, so the people who lived in the earth formed from his own body believed. But do legends just vanish? Wait. You might be asking what kind of legend I call him?
Well here's your answer: you know any bitch who could copy abilities with his dick? No, certainly not. So why can't I call him the cock legend?
You might also be thinking, if he was a cock legend then why hasn't he reproduced a nation?