Whats a streetfighter to you? A brawler? To me some brawler on the street will always OWN against some of the more POPULAR martial arts (TKD or Karate). Why? Because their techniques are not realistic. Muy Thai and BJJ is taking Martial Arts and being a realist with them. Its taking multiple arts that all ahve their weaknesses and satisfying those weaknesses with an art that prevails at it.
Are you to say Matt Hughes (Big striker and grappler), Anderson Silva (Legendary Muy Thai fighter), even Royce Gracie (BJJ), would get owned by some bouncer brawler in a bar? Not likely.
Most of those type of streetfighting brawlers I think of have no technique, or skill, just rely on throwing 10 punches, hoping 3 will hit.
Now Im not saying Im going to go out and pick some fights, but just defending the FACT that most brawlers as you mention have no technique or idea of what they're doing, and will always get owned by a skilled Mixed Martial Artists. I've also had my fair share of bar fights out in a parking lot (before I began MMA), so I know what I mean when I say Brawler.
BTW, i reread this post, and Im not arguing. Just sort of debating back with you...