Juve where 12 clear when they won the league mate, napoli closing by 3 points after that point was irrelevant, as Juve had already won it.
As for saying they have no hope and comparing them to City and United.
City and United both can outspend Chelsea, neither would lose their star player to Chelsea either (like Napoli did with Higuain)
Both City and United have a lot of trophies in recent years, Napoli last won the league when Maraddona was snorting Italian coke.
It finished with 9 points difference all things being equal.
I know Juventus is highly likely to walk the league each year but saying that Napoli isn't a contender is laughable. They are the second best team in the country and after Juventus would probably be considered by most as the most likely team to win Serie A.