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Morrowind and Heroes 5 were developed by teams much larger than 1-5 people.
At the time of Heroes 5's creation, Nival had several hundred employees, as far as I know. The creation of resources, such as models, was often outsourced. That is, you need to add even more people to the staff.
Now, a logical problem. One 3D modeler creates, say, one model per month. How many models will 30 people create in a month?