They DO have formal training, it's call Filipino martial arts/stickfighting primarily.
All that shit they do, it's how to effectively crush someone's skull in with a fucking heat-treated ratten stick which can fuck you up about 9000 times harder and faster than a haymaker can.
If you wanna talk about "realism" or "hardcore" these are the LAST guys I would talk shit to in their face. I train Muay Thai 4-5x a week and preparing for smokers and I would say that I'm an alright fighter, but let's be real, even if you are professional MMA fighter, it's pretty goddamn hard to beat a guy armed with knives, sticks, and tazers and fights FULL CONTACT learning how to use those things as dangerously as possible.
So yeah, Dog Brothers have been around for AGES and are basically the epitome of "realistic and dangerous training." Don't like it? That's cool, it's not for everyone definitely. But to call them "retarded" or things like that? Why don't some of you fucking nerds show up at one of their meets and talk some shit, they would probably shatter your kneecap if you actually manned up to "spar" with them.