I didn’t pay close enough attention to the article about the woman with 9 ft hair to notice that she had dreadlocks. Not that it would’ve made a different impression on me – I didn’t realize that dreadlocks contained hair no longer attached to the scalp.
Actually, it is intended on some breeds. Not long manes & tails, but thick, slightly longer, fuzzy and warm coats are a trait of some horse breeds that come from the far north – Shetland ponies & Norwegian Fjord horses, for example.
And breeds that come from hot desert areas, like the Arabians, have shorter, thinner, sleek coats, and a tendency toward light, sun-reflecting colors (white & grey).
No doubt because of a combination of these occurring naturally, but human owners recognizing the usefulness of the trait and breeding for it.
What breeds, please? I assume you’re not going to tell me that breeds (such as the Afghan and Komondorok) which were developed for purely utilitarian purposes are among them. I can readily believe it of those breeds which were developed as pets, and possibly of some breeds developed in the last couple of centuries. But in breeds of any domesticated animal developed in earlier times, the stockbreeders selected for those animals which could best do the job they were wanted for (or were the tastiest, or exhibited other useful or desirable criteria). Characteristics such as coat type and color were irrelevant to their performance. But the ones with longer coats were more winter-hardy. That gave them a survival advantage.
The Saluki - which, like the Arabian horse, was also a desert dweller - does have the light, short coat. Indeed, there are some Salukis which don’t even have feathering. The Pharaoh Hound (a closely related breed, even though they have prick ears and a somewhat different head) doesn’t have feathering at all. I know that “my” breed, the Great Dane, has been significantly streamlined by breeders in the last century. Their ancestors needed a heavier musculature, given that they were used for hunting wild boar. The modern Dane is far more beautiful, but if I were picking a dog to use for boar hunting, I’d prefer the earlier version of the breed. Not to say that many Danes couldn’t do the job; it’s just that they would probably not be able to do the job quite as well. And, of course, they’d need the ears not merely cropped, but cropped off, to prevent them from profuse bleeding when their ears were torn.
Your example of Arabian horses tending to be primarily light in color is a functional characteristic. A dark coat - black or bay, or even chestnut (none of which reflect light very well at all) would promote overheating, which would be detrimental to the horse’s stamina - and quite likely - to its existence, if it were called upon for sustained effort during the hottest part of the day. What’s more, the pale colors more readily blend with the colors of rocks and sand - the vast majority of the territory in which they lived and were used.