Because goats produce their own spinnable fibre – notably the Cashmere goat breeds and the Angora goat, which produce cashmere and mohair respectively. Yes, mohair – not angora, which is produced by the Angora rabbit.
Historically, or rather paleoagriculturally, sheep appear to have been bred primarily for their wool, whereas goats seem to have been bred primarily for milk, although there are such things as milk sheep and, clearly, fibre goats. I can only hazard a guess that the primitive sheep domesticated by our ancestors must have produced more fibre than goats did*, and/or that primitive domesticated goats had more milk or were easier to milk than sheep
Yep, definitely easier to milk the goat.
* – The Jacob sheep, a relatively primitive breed, produces about 2–3kg fleece, whereas (modern) Cashmere goats produce only 1kg.
Organic anything is not necessarily better, and in many instances much ‘worse’. Organic vegetables, for example, are often smaller because they are grown in natural fertiliser (dung) which has fewer nutrients; they may have minor blemishes and scabbing, because they are not treated with commercial pesticides which produce better results, and so on.
Organic wool comes from sheep who are grazed on naturally-fertilised land – which may have less grazing, of less nutritive value. The sheep themselves are not given certain medications, and not put through certain dips, so they are potentially less healthy. The wool itself undergoes processing without the usual chemicals. Undernourishment, and limited veterinary intervention, can produce a finer wool*, though usually in smaller quantities. The finished yarn, organically processed in organic-only mills, can be greasy and full of VM**. Some people love this, others get hives at the thought. Come to market, it’s pricey and usually in limited supply – so no wandering in a month later when you realise you need just one more ball.
I rarely use organic wool myself, but much of my knitting is for pattern-writing – there’s no point in me writing a pattern for that limited-run almost-organic mohair-Wensleydale blend produced by a nice lady vet locally, because by the time it would be written, she’d be sold out of this year’s shearing. But I do bagsy a few batts to spin myself, and make a cowl or gloves just for me, and I know she doesn’t starve her animals or deny them treatment. Lesson being: buy organic when you can visit the sheep it comes from.
* – The best cashmere comes from half-starved desert and mountain Cashmere goats, not their well-fed and well-cared-for brethren in the south of England (ND: half-starved because the native forage is so poor. Not because they’re denied food).
** – Vegetable matter. Twigs, hay, thorns, and occasionally poop.