Well, those links present a whitewashed “history”. To begin with, the Mormons in Cedar City viewed blood atonement as a literal practice, not a theory. Before the Mountain Meadows Massacre, there was an instance where it was practiced, as testified to by John D. Lee at his confession for the Mountain Meadows Massacre:
"In his confession, Lee offered a chilling account of one instance of blood atonement in early Utah:
"Rasmos Anderson was a Danish man who came to Utah… He had married a widow lady somewhat older than himself… At one of the meetings during the reformation Anderson and his step-daughter confessed that they had committed adultery… they were rebaptized and received into full membership. They were then placed under covenant that if they again committed adultery, Anderson should suffer death. Soon after this a charge was laid against Anderson before the Council, accusing him of adultery with his step-daughter. This Council was composed of Klingensmith and his two counselors; it was the Bishop’s Council. Without giving Anderson any chance to defend himself or make a statement, the Council voted that Anderson must die for violating his covenants. Klingensmith went to Anderson and notified him that the orders were that he must die by having his throat cut, so that the running of his blood would atone for his sins. Anderson, being a firm believer in the doctrines and teachings of the Mormon Church, made no objections… His wife was ordered to prepare a suit of clean clothing, in which to have her husband buried… she being directed to tell those who should inquire after her husband that he had gone to California.
"Klingensmith, James Haslem, Daniel McFarland and John M. Higbee dug a grave in the field near Cedar City, and that night, about 12 o’clock, went to Anderson’s house and ordered him to make ready to obey Council. Anderson got up… and without a word of remonstrance accompanied those that he believed were carrying out the will of the “Almighty God.” They went to the place where the grave was prepared; Anderson knelt upon the side of the grave and prayed. Klingensmith and his company then cut Anderson’s throat from ear to ear and held him so that his blood ran into the grave…
‘As soon as he was dead they dressed him in his clean clothes, threw him into the grave and buried him. They then carried his bloody clothing back to his family, and gave them to his wife to wash… She obeyed their orders… Anderson was killed just before the Mountain Meadows massacre. The killing of Anderson was then considered a religious duty and a just act. It was justified by all the people, for they were bound by the same covenants, and the least word of objection to thus treating the man who had broken his covenant would have brought the same fate upon the person who was so foolish as to raise his voce against any act committed by order of the Church authorities."’
law2.umkc.edu/faculty/projects/ftrials/mountainmeadows/atonement.html
Then came the wagon train, from Arkansas, passing through Cedar City. The local Bishop’s Council already demonstrating its belief in blood atonement. There was a strong sense among Young’s followers that those who murdered Smith should atone for the blood of that man. It was rumored that there were men in the Arkansas party who had participated in the mob that murdered Joseph Smith, and in the killing of Parley P. Pratt. The Council chose to act, and under the guise of Native Anericans and a false white flag of truce, murdered the entire party except the youngest children who they kidnapped, intending to raise as their own.
Blood atonement was most certainly a major factor in the Mountain Meadows Massacre and is swept under the rug.