I bought a mountain bike because it's more versatile than a hybrid.
Hauling the old bike with the new one because the old bike has carbon seat stays and is unlikely to survive the hitch clamp. The trails the hybrid can handle are limited while I've yet to encounter a road that is too smooth or too flat for a mountain bike to handle.
My hybrid can't haul much, can go off-road but not very well. Limited to light duty on-road, light terrain off-road. Fun ride though.