I have to push back a little on this. There are many paths to victory. Most of the extremely dangerous guys I know learned how to not "stack bodies" and not get in physical fights. In my business if you get in too many physical struggles and too many gunfights, the experienced guys(the ones who deeply understand survival) start seriously questioning your judgement, your ability to learn from your experience and you tactics.
"Stacking bodies" is not a sign of proficiency as it pertains to RBSD. And if someone has a high body count as a military door kicker, great. But that does little to qualify someone to effectively teach RBSD. It just means they kicked some doors.
If you are unarmed, and at bad breath distance and are in a fight for your life, a significant factor is going to be who has better MMA type/sport martial arts type skills. People who stack bodies are vulnerable the same as everyone else.
If you are good, you avoid ever being in an unarmed, bad breath distance fight. If you are good, you master never being in a situation where you fight from a position of disadvantage. That's how you survive multiple encounters.
But if you want to learn to fight from an extreme position of disadvantage when you are unarmed, the number one skill to posses is MMA type skills. I don't care if you are SWAT, SEAL, Ranger, SAS, or batman, this remains true.
If you are someone who "stacks a lot of bodies" and you have a super ton experience with physical confrontation, you are doing it wrong.