Partly, but overall no. The arcs are only good and their structure. The flashbacks help, but most arc relies on many factors outside of flashback that makes their deliveries unforgettable.
Robin "I wanna Live" is created by the pressure of the flashback but the structure of the arc. Sanji's "I wanna go back to Sunny, but I wanna save them" And Luffy's answer "that's who you are" are not carried by the flashback but by the entire desesperation of Sanji Etc.
In many cases, flashback can be the fuel, but without the story, the arcs wouldn't ride the hype wave.