For dry camping in comfort freshwater capacity & battery capacity is king. Unfortunately RV builders seem to think that everyone camps in FHU CGs these days. Residential fridges are common. Room for batteries is extremely limited. Grey water tankage is inadequate. Fresh water tankage is way inadequate.
Many large class A MOHOs have adequate tankage & house battery capacity but you seldom see these units in dry camping areas. They are too big for most of these CGs & maybe the owners want all of the comforts of home.
5ers typically have loads of unused space under their floors & in their basements for larger tanks & more battery space but this space is seldom used or underused.
Some of us actually like to dry camp in comfort. A TC or TT simply cannot provide the tankage needed to do so.