My stud isn't that popular. My interest in the science doesn't justify the expense. It hurts regional breeding. Can't teach stud to collect. Can't find a mare ready to arouse the stallion in time.
Motility is a major factor.
The ranch is too far from the vet. Too many variables increase the room for error. Time and delivery are too critical. Complex routine is too much of a problem for the trainer-breeder. AI has reliability problems beyond the control of the smaller operation.