1:1 fighting is extremely exceptional from a real world perspective. All real world fighting will be either many:many, or 1:many, or you should assume so as you never know that your assailant doesn’t have a friend somewhere nearby.

If you engages in BJJ like ground fighting techniques, it’d be like that scene in Indiana Jones where the crazy swordsman final boss shows up, and Indy just shoots the guy. Some other guy would come over and step on your neck, stab you, or just shoot you while you’re down, or your opponent will gouge your eyes out, because that’s the real world response. Historical fighting manuals are pretty explicit: never, ever get caught on the ground or you’re dead.

It’s just that most of the ways in which a standing person would attack a nearby person on the ground are so dangerous that they are outlawed from sport competition, and so ironically even the notoriously “everything goes” MMA ends up favoring ground game and devolve into wrestling matches.

Many organizations need to train people for real-world fights. Think police departments, militaries, prison guards and the like.

By far the most popular thing to teach is some variant on Krav Maga. Which focuses heavily on rapid incapacitation while maintaining your ability to move. Going to the ground wrestling is an excellent way to be taken out by your enemy's ally, or finding out the hard way that your enemy had a hidden knife you didn't know about.

The success of BJJ in MMA has not changed what gets taught to people who actually are at risk of winding up in a street fight with lives on the line.

MMA fighters are often asked in interviews about techniques for real street fights. The answer is always to sucker puck then gouge the eyes and throat.

BJJ is well suited for the octagon. Allow small joint manipulation and most of the technique goes out the window.

Yes, sport fighting is not like survival fighting because anything that would cause permanent damage is against the rules. Against the rules doesn't get trained or practiced.