Guarding a farm or property is one of the fundamental tasks certain dogs were historically bred to execute. Guarding a farm or a herd of sheep from wild predators or human thiefs was existential for the farmer or shepherd.

The dogs job never was actually attacking the intruder - be it a human or wolf, for example - but to bark and either scare the intruder away or make the farmer aware of the intruder to come and help the dog. If the dog were left all alone on farm, it couldn't do an effective job of guarding it.

The Wikipedia article writes about "northern Midwest farms". It's not clear what type of farm is meant, but this article What do farmers do in winter? lists some activities common to various types of farmers. Especially animal farmers would have to be out with their herds during winter to make sure their water supplies or machinery don't freeze and to collect newborn animals and bring them into a warm pen. That doesn't mean that the farm is abandoned for any lenghty amount of time.

If you change the emphasis on the Wikipedia article, you might notice that the last sentence doesn't necessarily refer to the first.

The rough collie's long coat has made the breed successful on northern Midwest farms as an able herder and guardian of the farm during the winter. The dog needs to be gradually acclimated to the cold and a suitable insulated outdoor shelter must be provided for the dog along with ample quality food and a source of unfrozen water. The rough collie also relishes playing in the snow with children during the winter months. They guard the farm while the owner is away and are naturally protective of small children.

The first sentence is about the dogs ability to thrife in colder climates, but the last sentence is about its proctective personality.

Guarding a farm or property is one of the fundamental tasks certain dogs were historically bred to execute. Guarding a farm or a herd of sheep from wild predators or human thieves was existential for the farmer or shepherd.

The dogs job never was actually attacking the intruder - be it a human or wolf, for example - but to bark and either scare the intruder away or make the farmer aware of the intruder to come and help the dog. If the dog were left all alone on farm, it couldn't do an effective job of guarding it.

The Wikipedia article writes about "northern Midwest farms". It's not clear what type of farm is meant, but this article What do farmers do in winter? lists some activities common to various types of farmers. Especially animal farmers would have to be out with their herds during winter to make sure their water supplies or machinery don't freeze and to collect newborn animals and bring them into a warm pen. That doesn't mean that the farm is abandoned for any lengthy amount of time.

If you change the emphasis on the Wikipedia article, you might notice that the last sentence doesn't necessarily refer to the first.

The rough collie's long coat has made the breed successful on northern Midwest farms as an able herder and guardian of the farm during the winter. The dog needs to be gradually acclimated to the cold and a suitable insulated outdoor shelter must be provided for the dog along with ample quality food and a source of unfrozen water. The rough collie also relishes playing in the snow with children during the winter months. They guard the farm while the owner is away and are naturally protective of small children.

The first sentence is about the dogs ability to thrive in colder climates, but the last sentence is about its protective personality.