The original Persona from 1996 was the first Megami Tensei game to receive a release outside of Japan and be localized in English, bringing new fans to the franchise. Persona 3 from 2006 was the first time the franchise achieved huge international success as a unique jRPG (however broad this genre name is). Persona 5 from 2016 was the first time the franchise reached a success that went beyond the genre boundaries.
Of course, the process wasn’t that rapid and sudden and this “every 10 years” view is incorrect – each new game built momentum, gradually growing in popularity. And it’s not even that every odd release of Persona games is meant to be an important milestone, because then we will have to discuss many re-releases, spin-offs or even the fact that there are 2 games called Persona 2, one of which is a sequel to another. What is important, however, is that Persona 5, in its Royal release now finally available on most platforms, is the first time I wouldn’t have any trouble recommending a Persona game to absolutely anyone. With no asterisks, links to wikis and complex explanations. Persona 5 Royal is just that easy to get into. And also really hard to stop playing.