Hanzou
Grandmaster
Somebody comes along and has some success with an art and people start to worship it. It usually has to do with what people see in sports, TV and movies. There was Karate' back in the day, then Kung Fu (like that was just one thing!), then whatever Bruce Lee was doing. Krav Maga and BJJ are having their day. In ten years, it will be something else. I am noticing in UFC, which seems to be everyone's yardstick, the grapplers are still in there, but the punchers are making a pretty good show too. Even some Wing Chun with Anderson Silva. Now there is "folk wrestling" like Kabib giving the BJJ guys a run for their money.
Except, BJJ has been "having its day" for nearly 30 years. It's not based on movies, it's based on effectiveness (and a rather appealing MA culture). Pure and simple.
The Karate and Kung Fu phases ended because (as you stated), they were popularized by fiction. BJJ was popularized via an actual martial arts tournament.