The difference about Gibbon in his writing is that he was motivated by a cause, a righteous one at that. But he personifies a version of the pessimist. For instance, when other writers saw a harmonious and blemish-free Scotland, he saw the mines where the slaves were chained, and nothing else. With the Sunset Song, he might have written about the triumph of the human spirit but there were no other notes on the redeeming factors of man and nature. This is the reason why he was easily frustrated by what he saw in his peers. There is such a fatalistic attitude that might be over the top especially with what he said in his letter to Helen Cruickshank. The world may be cruel but he is not alone in the crusade to do something about it. He has his ways but others do as well. A positive consequence, however, is that Gibbon was able to write modernist fictions that not only depict reality vividly but also make people notice and change perspectives.
Lewis Crassic Gibbon A Commentary