There is no "theme" lol.
- Luffy got a 30 Million bounty for defeating 3 pirates with bounties, not just Arlong
- Das Bones had a 75 Million bounty, Zoro only got 60 Million for defeating him.
- Next bounty increase had nothing to do with Pirates....so your argument makes little sense here.
- Luffy alone got a 100 Million increase for the Tenryuubito, Impel Down and Marineford incidents
- Then he "only" received a another 100 Million increase for Doflamingo, who very much was stronger than other 500 Million pirates. Hell, fucking Lao G 1 shot a 500 Million pirate, who then was 1 shotted by someone else. The rest of the crew received. The only exception was Franky receiving a 30 Million increase for defeating Senor Pink, who had 58 Million. Granted, the Donquixote pirates all have frozen bounties, so they are lower by default, thus someone like Franky getting a 30 Million increase is justified. People like Sanji, Nami, etc didn't even do anything....and they got increases by virtue of being affiliated with the crew.
- Then Luffy got a billion increase for defeating 2 Yonko Commanders, destroying BMs castle AND getting away with it. Common misconception is that he only got a billion for Kata. That is FALSE.
- Finally Wano just straight up showed that Luffy, Law and Kid did not surpass the Yonko bounties they defeated. And again, Sanji and Zoro managed to defeat YCs, but if you understand the above with WCI, you should KNOW why their increases aren't as high as Luffy's was, outside of the fact that he is a captain of a dangerous crew. Jinbe has notoriety. He was a former captain. He was a Shichibukai. He's stronger than people think.
So no...I'm not seeing your point lol.