::The appearance of the teacher-tulku system is as much a political development related to Mongolian political dominance in Asia as it is Tibetan understanding of the bodhisattva and the teacher-student relationship. I did misspeak about the Sakyas; it was in fact the Karmapas who were first. (I should have remembered given that I recently rewrote that article, but it was late...) Qubilai was his first patron, who he passed over for Möngke, who was the Khagan at the time. His importance in the Imperial Court was followed by the rise of a political elite comprised of newly-minted teacher-tulkus. The coinage of new tulkus never ended since then. And the relationship between the new tulkus wasn't always some random child: the first of the brand-new tulkus of Jamgon Kongtrul in 1902 was the son of the 15th Karmapa. The Sakya, in contrast, had a physical lineage: its leadership passes down through the Khön family. It was the importance of the Sakya as appointed leadership of Tibet by the Mongols that was contested by the Karmapa. Many other lineages followed suit and the carrot of political power is obvious. We can't ignore the giant waving flag of politics in these matters no matter how worldly it seems. 
 ::As for why we can't delete that section: well, as the cite says, "The establishment of the teacher-tulku system for the Karma Kagyu lead to other schools of Tibetan Buddhism creating similar systems. (Buswell 2014:421)" It is the ultimate origin of the religio-political power of the Dalai Lama lineage, which ruled Tibet for a Very Long Time. Six sentences is not undue weight when it is literally an explanation for the rise of the tulku system. I'd actually like to make it five sentences, because it seems to me that this bit contains peacock terms: "Before his death in 1283, Karma Pakshi wrote a will to protect the established interests of his lineage, the Karma Kagyu, by advising his disciples to locate a boy to inherit the black hat. His instruction was based on the premise that the Dharma is eternal and that the Buddha would send emanations to complete the missions he had initiated. Karma Pakshi's disciples acted in accordance with the will and located the reincarnated boy of their master.[citation needed]" I actually can probably find a cite but I'd shorten that bit. 
 ::So. That's my reply. I didn't mean to sound difficult or whatever, I was just trying to be direct. As for sounding learned: well, I've been wading in deep waters but I doubt many people really understand what is going on in the entire world.