I never ever suggested that a dog should be off-lead anywhere near sheep. Nor did I advocate taking a dog so close to sheep that it got excited and disturbed the sheep. If you actually read my posts that is completely clear.
I want my dogs to be as steady as possible around other animals. As @Ihaventgottimeforthis points out, management fails. Your management of your dog. The farmers management of the stock (which is not a criticism, just a fact of life -lambs escape). Or just some arse has cut a fence (we had cows out here recently, because someone cut a fence).
So there you are, out in the village playing fields before work, responsibly exercising your off-lead dog who recalls away from picnics and other dogs and even rabbits. And on the far side of the abutting arable field are sheep in a pasture. A tree came down in last night's wind and took out part of the fence, and a few ewes decide that the grass is greener. And you don't know it, but they're behind that clump of brambles in the corner behind the rugby pitch.
And out they trot, 50' in front of your dog, who is 30' from you.
What's best then? A stock-broken dog who will stop on the whistle, or one who goes into prey drive?
Oh, and I recommended sheep 'not in lamb' because I wouldn't want to so much as disconcert in-lamb ewes.
Because, as I said before, I'm not 'fucking insane'.