Light riders are at a big disadvantage on crits in the Zwift category system. Crit speed is a mix of raw power and W/kg (only climbs are dominated by W/kg). The bigger you are, the more capacity you have for watts. The categories are based on only W/kg though. Also categories are based on 20-minute power, and crits require exceptional 5 minute power to survive the start, and 30 second power to survive surges. So a light, endurance-oriented rider is at a huge disadvantage: by the time you’re fit enough to be competitive in the D’s, you’ll have been upgraded to C.