Please: tell that to the hundreds of thousands of racers in Zwift, that the racing categories having nothing to do with watts per kilogram, but rather “just weight classes”. You might find yourself in a bit of a pickle. LOL.
The expression “that’s the way it’s always been done before” is self-evidently an obstacle to progress and enlightenment. As Ayn Rand famously repeated, “Check your premises”. If your premise is based on some variation of “that’s they way we do it IRL”, perhaps your premise is flawed? Let’s just acknowledge that there are differing ways of examining the W/kg / weight / velocity issue, and be prepared to change your mind. Remember how many professional racers were blown away in the their first Zwift races? Things in Zwift are slightly different than in the real world.