I am not going to post anything that is against Judo or BJJ, I don't intend to start a war. I will state that in my opinion, LE has requirements that are not as conducive to ground games as one might think.
For one thing, a LEO typically has a small arsenal of weapons on their waist. All of these are designed to be deployed quickly, which means they can be removed from the belt fairly easily. We do not want to be closing with a person whose hands are not yet secured or is facing us. Drunks try to grab guns, sorry, it's a fact. We don't want them anywhere near our weaponry. That meant for me in the old days, I'd use my Monadnock to club a drunk who reached for my gun. I'd drop him like a baby seal and no mercy either. He gets my gun, I'm done.
Second, even if you know how to fall correctly, it can be damned difficult to do it safely on asphalt, gravel, ice, snow, blood, or whatever you find yourself standing on. And then you have to worry about falling ONTO things which are sharp and pointy, like guns, handcuffs, cans of pepper spray, radios, etc, etc.
Third, stuff goes flying. Watch a cop fight video sometimes when it goes to ground. Please note that typically the cop does not voluntarily go to ground unless he's on the suspect's back in a kneeling position. And even then, his stuff goes flying everywhere, from hat to badge to radio and even sometimes his or her gun.
Fourth, sometimes more than one suspect. Great way to get kicked in the head by bad guy's drunken buddy who thinks he's helping his buddy out. Even passersby who are TRYING TO HELP can get decked because we don't know why a person without blue sleeves is trying to pry something loose. Not that we hate good Samaritans, but we don't know who is who unless they're wearing a badge.
Fifth, most departments these days forbid the use of choke holds. There are lots of things that a civilian can do to defend themselves that are forbidden to cops.
Sixth, we don't fight fair because we cannot lose. Losing is not really permitted. So if Jojo the dogfaced boy reaches for us to bring us into a clinch, he's going to get his hands broken with a night stick. Ball up a fist and try to throw hands, get a stick in the face. Not fair? Too bad, don't attack cops and you don't get mussed up. Get your hands on one of our weapons and we shoot lots of holes in you. That's how that game is played. Civilians do not like to hear about it, but it's true.
There are some rules to cop self-defense, because it's a different game for us (again, formerly in my case) than for most. We have to engage, most civilians can and should walk away. We often engage groups, so it's not a one-on-one thing. Macho don't enter into it, it's about making an apprehension and ending the danger to the public. Speed of apprehension is much more important than the attacker's safety. And lastly, we do this far too often. Our job is to end the danger, make the arrest, do the paperwork and GO HOME SAFELY. Attack a cop, you get what you get. Not trying to hurt you, but you not hurting me is much more important at that moment.
Go to the ground? Not if I can help it. Does it help to have a ground game? Absolutely, because sometimes you can't help going to the ground. But my first go to is verbal. "Ask 'em, tell 'em, take 'em." If that doesn't work, it's hands-on. If they do not cooperate, it's time to apply some come-along type moves. They go fistic on you, deploy weapons, and Hell comes with me.