Insecure is only seeing my comment in the scope of a pissing match, lol.
The appeal of Luffy for the first fifteen years I followed the series, and why he revolutionized shonen, is that he bucks strength conventions. He fumbles against enemies he should beat, gets kidnapped without even knowing, runs mid battle, loses consecutive bouts, utilizes allies at every turn, drew even with his own number two, and just plain gets lucky as he did with Ener. I think the only time his strength was played straight was Enies lobby.
So bragging that the main character beats the main antagonist, in the context of who Luffy is and how Oda uses him against guys like Kaido, is dumb. It's like bragging about a perk of a contract that's protected by a clause and naturally, it feeds into the appeal of the character who takes grievous wounds on his behalf to ensure the greater victory.