I guess people are unique. My body simply would not ever have the combination of power that high and a weight high enough to bring the w/kg down that much. I mean, I would have to eat like a madman. Like, eat more than I'm even willing to eat just for fun. Even then, the hours riding at the power necessary to get to that level of power..........that's even more calories in.
I think that disconnect is why it's hard for me to comprehend. I follow a coworker on Zwift from Denmark. Dude was a Danish national roadie or something at some point earlier in their life. But now they're quite a bit larger as they've grown older. They'll average into the 300's up Alpe du Zwift but I'll only put out like 250w and have a faster time by a couple minutes. So I do not question their power abilities at all. Dude has done nearly 400w for 20min in the last year at some point.
If I put out power like that all the time, my body would just disappear.
Maybe closer to a time trial race I should try to put on a few kg extra (just enough to still fit the skinsuit).