I think there's also something about too much defense/avoidance in the rules. I'm sure that description is entirely acurate and precise.That's how I understand it. You can't grip below the belt I believe, and certain other grips are banned. Which is why so many in Bjj go to wrestling over Judo, because the rule limitations in Judo require a complete reorientation of your training, whereas translating wrestling to Bjj is far easier.