the point I was making is that if he hadn’t meddled the rabbit population would have gone down naturally but him killing off the diseased ones was protecting the rest so they thrived.
You know this how? Rabbit populations normally increase until they reach the carrying capacity of their surroundings (i.e. they run out of food), or Farmer Giles or a local pest controller goes after them due to the crop damage they are causing, or a myxi epidemic sweeps through. Believe me, when myxi comes back around (as it does, every 4 or 5 years) it decimates the local rabbit population, from loads to few in the space of a season. If rabbits are dying of myxi, the rabbit population isn't usually increasing: it is going through the floor.
Are you saying that you would rather live a lovely life for 5 years then die or live free and make your own way in the world even if you were cold and hungry some of the time.
It doesn't work like that in the wild. The majority of young animals that are born either do not make it through to adulthood, or do not survive for long as independent adults. They can't: the natural environment doesn't allow it, even taking humans out of the equation.
Think about it: a lowland red deer hind will have a calf each year from the time she is herself about 2 years old old. If she lives to be ten or twelve (a fairly normal lifespan for a successful hind), she will produce 8 or 10 calves. She only needs a couple of these (20-30%) to survive to reproductive age for the population to remain stable. Of these 8 or so calves, some will die young of predation (if we're talking about an environment where the apex predators are still around) or sickness or, in a lean year, of hunger. Others might die of injuries (quickly if they are lucky, slowly if not). This is even more true of animals that produce large litters (e.g. fox, rabbits).
Contrast that with the average lamb: even lambs born to hill ewes have an average survival rate to maturity of >80%. This is because the ewe will have been wormed and probably given some form of supplemental feeding, so she is in good condition during her pregnancy and lactation and should produce a healthy, good-sized lamb (or lambs). Animals like crows likely to predate on lambs will have been controlled by the farmer and, in the UK, some predators (wolves, for example) were wiped out long ago. If a lamb suffers a cut leg, say, the farmer will probably see this before it becomes infected, maggoty and fatal and will bring the lamb in and treat it.
And in any case, a sheep doesn't stand in a field and think, I would love to be FREE. In fact, when sheep are on more open range (the hills of the Lake District, for example) they don't wander far. They are what is called hefted, which means they stick to their home ground.