No offence intended but implement in OP's photo isn't what was originally referred to as a rotary hoe. Shown in photos below is some of the first rotary hoes
Yea, that's actually not a rotary hoe but it is a tiller. PTO driven rotary hoes around these parts were for cultivating crops. Looked a lot like a tiller but had the empty row spacing for the crop. That implement is just missing a row or two of tines.