Having trained BJJ and some Judo, I have come to appreciate the idea that if you land a proper judo throw on someone in a street fight, i.e. on concrete, and you put someone down hard on concrete, the fight is almost certainly over.
The same applies for wrestling high-crotch or blast double. If you put someone down hard on the nearest solid object or concrete, there's a good chance the fight is immediately over.
That said, in a real scrappy fight, landing a proper judo through is a tall order. I've seen high level black belts fail to land clean throws on spazzy white belts. They get them down and technically win, but not cleanly, and not with the force needed to end the fight. Newaza (ground techniques, i.e. BJJ) comes in there to help finish.
Pure BJJ is great if you are fighting on dirt, and great to know defensively if you do find yourself ambushed or otherwise on the ground in an altercation. But in a real fight you should do your best to put the other guy down hard, get on top, and stay on top. Modern BJJ in particular is far too willing to concede top position, though modern MMA is thankfully pushing back on this some.