I mean, he has defeated Duran and lost a MD against Hearns and had a good fight against Leonard.

He's even one of the best puertorican fighter of all time.

Why isn't he remembered as the others?

Maybe because fab 5 doesn't sound as good as fab 4 or because he didn't fight Hagler. All the members of the fab 4 fought each other, Benitez only fought 3 of them.

His career was also on the downslide while the others got more and more popular. Benitez was never the same after he lost to Hearns.

Benitez did own Duran and had a good showing against Leonard and Hearns.
He never got any rematches though.

Why is he not in the Fab 4? Who would he replace on the list? Honestly. You could make a better argument for someone like Mike McCallum, and no way he replaces any of the original 4 either.

he never fought hagler coz he lost to hamsho.