If I remember correctly, the advice to give raises randomly also appeared in a serious, non-ironic "How to become a CEO" book [1].
There, it was positioned as a way to make subordinates work harder and make them more loyal - people were assumed to react to fuzzy, random bonuses and raises better than to a linear relationship between results and pay.
This is how you reward children for good behaviour too, without decreasing their intrinsic motivation for said activity, a good reference for how to motivate without using money is "Drive" by Daniel Pink.
There, it was positioned as a way to make subordinates work harder and make them more loyal - people were assumed to react to fuzzy, random bonuses and raises better than to a linear relationship between results and pay.
[1] https://www.amazon.com/How-Become-CEO-Rising-Organization/dp...