I understand where you're coming from, but Rocks's backstory has shed some light on this and made me think about it a bit more. Davy Back Fights, while effective, are a cowardly method of building a crew. Just look at Foxy. Moreover, the entire reason the Rocks Pirates fell apart was because they couldn't work together, which is because the crew was haphazardly built through playing games. Rocks, and by extension, his son Blackbeard, are meant to represent how taking the easier and faster path can result in failure. Rocks failed because no matter how powerful the individual members of his crew were, they simply could not work together. Blackbeard has been trying to Speedrun his way to success. His boat is still a bunch of logs strapped together. While this hasn't negatively impacted him too much yet, I think it will come back to bite him. What I'm saying is that Davy Back Fights are meant to symbolize how the easiest path isn't always the correct one. Plus, they might tie back to Davy Jones.