Why are people treating Luffy as a bum after the Chapter

I have seen soo many people saying " ofc Luffy lost he was fking around" I have to wonder are you guys reading the same story. Yes Luffy was on imu's lvl but its pretty clear that luffy was objectively in this fight at his strongest the main reason luffy lost is because imu has fought joyboy before " basically a almost prime luffy with better mastery over the df"