To give you a real world example:
My 2005 F250 had a Dana 60 front axle and Visteon Sterling 10.5 rear axle. Ford used base 17" rims rated at 3100 lbs and 3200 lb rated tires on this truck. This F250 was optioned with the camper package, it had upgraded suspension and stabilizer bars but was capped at 9800 lb GVWR due to its Class 2B vehicle classification. Even if the truck had the 3650 lb 18" optional rims and tires, it would still be limited by the class under which it was sold, but part for part would be identical to their higher rated Class 3 F350 SRW except for shorter rear axle blocks and badging. This is a case where you can order a vehicle that is strictly held back by paperwork in axle and gross weight ratings yet using all higher rated manufacturer parts from the next class of vehicle.
Now if you dig deeper into this same truck you will find that the front axle assembly from Dana is actually rated for 7250 lbs, but Ford puts in coils rated 4000-6000 lb based on application and options. The Visteon rear axle assembly is 9750 lb model that Ford suspends with 6000-7250 lb rated springs. The frame is the same one they use all the way through F350 DRW, so you know that it can handle 12,500 lbs or more in this application. So is this truck really limited to the sticker or is it marketed to particular segment with common parts across models which are cheaper to supply even if they have a higher rating? This information is not available in an easy to view chart for everyone to see, but you can research any vehicle and find which parts cross over between them. If you know the OEM for the part, you can now research that part and find its design ratings. This does require work and digging into multiple resources that may not appeal to some people to find out what the actual limitations are of their vehicle - For those reluctant people, it is better to follow the tags. For those that do have an interest in what components are used in their vehicles, they have the ability to make informed loading decisions beyond what the door label states.
We can take this a step further by replacing the lowest rated component in a system (once you have done your research). The paper tag has not changed, but the weakest link has now shifted in capacity...