Mera Mera beating Magu Magu would prove that Devil fruit powers aren't everything and Haki can be used to overpower someone. Any mera mera user not being able to any magu magu user would be fixing their fates and OP isn't about that. It's about freedom.
Trafalgar Law beating Doflamingo would prove that Monkey D. Luffy isn't everything, and willpower as well as smartness can be used to overpower someone. Any non-protagonist holding a grudge and trying to fullfil his revenge not being able to do so would be fixing their fates and OP isn't about that. It's about freedom.
See how stupid that sounds? Law didn't beat Doffy, Wiper didn't beat Enel, Pauly didn't Lucci, but the fucking 2nd in staff chief who keeps taking Ls from Fujitora is gonna beat the FLEET ADMIRAL of the Marines even though Luffy has 10x more reasons to do so AND actual beef with the man in question? Delusional.