Since rabbits naturally are ground dwelling animals I think that a sensibility for coccidosis is a bred in fault, different in different lines or populations.
Here wooden hutches are standard, on old time farms they don't get cleaned often, just hay or straw added until the layer is several inches thick. I know people who still keep rabbits this way (and in awfully small hutches, not big enough to stretch, and I've seen claws that were a half circle...
). Anyway, it needs a good immune system to cope with conditions like that, so I think it's pretty safe to let my bunnies turn my garden into a Indiana Jones style Pit Trap Adventure Park. They sure came in contact with everything out there.
Many generations of wire cages could have changed something there.
Ok, that's just my crude theory, but that explains my take on Cocci: I ignore the fact that it exists until any problems pop up. I'm in my fifth year with rabbits, that's not much experience, and I'm not going to tell someone that my way is the right one for their bunnies.
But having the rabbits around me, running around and through the house, is a big part of why I even have them.
Hm, but I will look for plants high in tannins if that is good, I feed mugwort anyway to prevent worms.