"CGTrader Quality Standard" should be called "CGTrader PBR Compatibility Standard" as it has literally nothing to do with quality. A simple cube with a PBR material is still just a simple cube as a model.
PBR tries to standardize material and basic geometry properties to get matching results on renders. It has never been a "quality" standard.
If this "verification" was really about "quality" then every native (Blender, Maya, Max, C4D etc.) and every not native (obj, collada, stl etc.) formats would be checked as well not just fbx, as the asset should be equally "quality" in every format it offers .
Assets, wanting and claiming to be PBR compliant have to meet the requirements.
Assets, not wanting and claiming to be PBR compliant should be left alone.
Spending resources on a "verification" that the vast majority of assets don't want or need instead of spending it on a better working site...makes no sense to me.
Just my 2 cents...