What also goes in Napoli's favor is that in serie A it's almost always the best defense that wins the scudetto.
In the previous 20 seasons, in 18/20 years the best defense won the scudetto. Only in 2007 (Mancini's Inter weren't the best defense by just one goal) and in 2020 (Sarri's Juve) the best defense failed to win it.
The best offense won only in 8/20 seasons, but in 7 of them, the best offense was also the best defense.
Only once, in 2020 (Sarri's Juve), neither the best defense, nor the best offense won the scudetto, but that was the covid season and Juve practically won the scudetto very early, that we could allow conceding 17 goals in the last rounds and still comfortably win.
In short, if you have the best defense in serie A you're pretty much guaranteed to win the scudetto, and Napoli has it.