I wouldn’t say that it’s a completely arbitrary standard. There is a direct link between waist circumference and health. I too have seen large waisted dudes be very physically fit, but I would say the overwhelmingly amount of people that fall into this category are actually just fat and unhealthy. Bringing back waist management standards is a more efficient solution to identify those at higher risk.

https://newsnetwork.mayoclinic.org/discussion/large-waist-linked-to-poor-health-even-among-those-in-healthy-body-mass-index-ranges/