That is correct, it is Disney/
DVC policy that all guest be registered.
In Dean's example, as long as his group size and his friends group size total does not exceed occupancy, they can all be listed on the initial reservation.
For example, if Dean has a two bedroom reserved, and his group is 4 people, and his friends group is 4 people, all 8 can be listed on the reservation without segmenting. The fly in the ointment would be if either group wants a dining plan.
Now, if it was a two bedroom, and Dean's group was 6 people and his friends group was 6 people, that would be a problem, even without the dining plan. They could only all be listed in a segmented reservation.