"Social Stealth" as a Game Genre, or Why "Among Us" Died and Why That's a Very Good Thing

Have you ever played "Mafia" with a group of friends, where people get different roles and test each other's trust? Well, now it's also a separate genre of video games.
From mods in "Garry's Mod" to the "Among Us" boom, this genre is one of the most unexpected in the industry, because these games very quickly gain a huge audience and just as quickly vanish from the radar.
But why? Is it a problem of the genre or of the developers? And why is the death of the genre's king a couple of years ago a very good thing for new projects?