Outside of Quora Thread: An Lushan >100 years before the fall of Tang
Factionalism was responsible for the fall of China's dynasties
Factionalism was a factor in the fall of the Tang Dynasty
Factionalism was a factor in the fall of the Song Dynasty
Factionalism was a factor in the fall of the Ming Dynasty
An-Lushan rebellion weakened the central bureaucracy
Needs support/cites. The average person was screwed in China from at least 1000AD till 1950.
However, having looked at the Quora thread, I agree there's none there either.
The average person's dissatisfaction and poor living conditions were better predictors of the fall of a dynasty
This appears to be a frequent occurence in Quora's history section
Sustained infighting and factions in the emperor's court
Wikipedia article on the Song (linked to in Quora thread)
Factionalism weakened the dynasty at a critical point
Wikipedia article on the Ming Dynasty (linked to in thread)
As this is the only RPC study I've found following health of recipients for a sustained period, the result suggests broad confirmation bias