This season will be different, Napoli coached by Conte with the many changes they have made have shown very positive progress so it is worth being aware of regardless of Napoli's consistency which is still in doubt but I think Inter Milan is the same.
If you look at the strength and consistency of Inter Milan and Napoli, I am quite sure that these two teams will compete fiercely until the end of the season and also in terms of percentage, both teams are still quite equal to win the Scudetto title this season.
Napoli began this season after a past disappointed season and with a transfer of Osimhen out of the club, there was not big hope that they can compete for Scudetto and I believe that their main hope is competing for top four and be eligible for Champions League ticket next season. So far Antonio Conte managed much better than Napoli expectation and they are competiting for Scudetto.
With not too deep player resource like Inter Milan, Napoli will have to very focus on Serie A and protect their star players well, to avoid injuries that can affect their squad operation and performances when one or two star players have to miss several matches.
You are right, Inter Milan always has a big name and with a good history too, if compared to Napoli then we will find a lot of differences. Maybe some people will say that it is just history and what happens now could be different. That is not wrong, but one thing we can see is their journey too. When a team with a long journey they are always in tight competition and also win several titles, then mentally they will also be more trusted. This is a habit and in fact it happens like that. Not to underestimate Napoli, they are also a good team, but here we are just having an opinion.
Inter Milan have better history than Napoli as well as recent seasons, but their difference is not too big and this season shows this. They are very close in points and chance to win Scudetto opens for both of them. I agree that it's true to say Inter Milan theoritically are stronger than Napoli, but in a long season, if you make some mistakes, you will give chance to win a title to your competitor. Napoli are good enough to beat Inter Milan and win Scudetto and it won't be too big surprise like Leicester City story in Premier League years ago.