Guys like DC, GSP, Silva, Masvidal, McGregor, Sonnen, Holloway, Diaz, Edgar, Penn, etc are real martial artists that don't give a shit about weight. Infact. The term "Pound for pound" was coined for fighters in boxing that were not afraid to fight at multiple weight classes. They were the true P4P greats.
This is why Jon Roid Jones will always be a coward in the eyes of true fans of fighting.
Jones is fighting at his natural weight class his entire career. He never missed weight and he's skinny.
Your examples:
DC - he started his career at 265. He moved down to 205 because of Cain. He moved up because of Cain as well lol. He barely made 205. Cormier is a natural heavyweight and he shouldnt even be fighting once at 205.
GSP - he only cherry picked Bisping at this weight class. But respect, he beat Bisping after 4 years layoff and many injuries.
Anderson Silva - I agree. He always made 185 without any problems and he fought at 205 because lack of challenges at 185 in this time. But he was a big middleweight.
Masvidal - he's eating fast foods, he's getting old so he couldnt make 155.
McGregor - weight cutting expert. He looked like a zombie at 145. He knew Aldo fight will be his last fight at featherweight. He never fought at 170 against other person than Diaz. At 155 he only fought twice in UFC - it his natural weight class.
Sonnen - I agree, uncle Chael is not afraid of anyone.
Holloway - he's more lightweight these days, struggle to make 145. He tried at 155 but Poirier beat him. He should move up asap, its dangerous for him.
Diaz - he fought at 155 his entire career as a very big lightweight (at least long). He's 34, he dont want to cut so much weight so he's cherry picking opponents at 170 like Pettis. It means they are ducking 170lbs wrestlers.
Edgar - he is moving down, again. In his prime he fought at lightweight where ha was small 155er, very small and he was the legit champ. So respect for Frankie. Edgar should fight at bantamweight his entire career. I think he would easily make bantamweight in his prime, I dont know if now. He is nearly 38 years old.
Penn - I agree, Penn was a badass like uncle Chael.