Luffy need not to face his net opponent as under dog....tired of under dog shit....on one hand people hate shonen for "power creep" but on other hand, they are very much into "underdog" which is typical of shonen....fights can be interesting even without being an extreme underdog...Luffy was equal to Lucci with G2 and above him in G3....even then that fight is one of the best in whole shonen....
Yeah honestly an MC being stronger than most people can be a trigger for Oda to express the character exploration more, the payoff and admiration for the MC, the reward for all his struggle, where MC can outright punish those who are crossing the line etc. Luffy suffered so much from underdog syndrome that there was no more reward. Look at Luffy and Arlong, Luffy and Lucci, Luffy and Croc, their final round is much better than the initial round where Luffy was the underdog, because we get to know Luffy's expression and perspective about things (luffy vs arlong"i cant do this and that or this or that...but i can BEAT YOU.", luffy vs croc "I dont care who you are, but I WILL SURPASS YOU" , luffy vs lucci "If i let you go, you will kill my nakama. So will not look away from you." Luffy vs Usopp "you already know you can never beat me! ...it's heavy...")
Other than that, One Piece should be near its end already. Oda doesnt have time to make Luffy surpass Aokiji first, then struggle against Greenbull, then surpass him again etc. Since Luffy has the burden of entire world now. Shanks, then Blackbeard, Ancient Weapons, Imu. The ultimate gods are waiting for him to climb the final stairway. Oda doesnt have the luxury to make Luffy struggle against everyone, just these four is already plenty.